HomeSearch by dateVacation packagesHotelsFlight dealsCar rentalTravel tips & news
Key Largo

$55+ Cheap flights from St. Louis (STL) to Key Largo, FL

This is the cheapest one-way flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 1/31. Fares are subject to change and may not be available on all flights or dates of travel.
STL — MIA
Dec 3 — Dec 101
Wed 12/3
Wed 12/10
1 adult, Economy
We work with more than 300 partners to bring you better travel deals

Find cheap flights from St. Louis to Key Largo with Cheapflights

1. Tell us where you want to go

Enter your travel information like dates, passengers, trip type (one-way or round trip), and preferred cabin class then click “Find deals”

2. Select your favorite providers

We find the providers serving your travel needs. Choose up to four travel providers to compare side-by-side for flights, hotels, or car rentals.

3. Compare prices and book

Review each provider’s pricing and select the best option for you! Book through your favorite provider’s website for a seamless experience.

Cheapflights Tip: The best prices from Lambert-St Louis to Key Largo are usually found in September or August, booked 33 days in advance, depart on a Sunday or Tuesday and return on a Thursday

Find flight deals from St. Louis to Key Largo

Cheapest flights from St. Louis to Key Largo
Explore the most affordable flight options available from St. Louis to Key Largo. Find the lowest fares from popular airlines and budget airlines, with prices last updated on November 3, 2025.

This Kiwi.com deal was found by Cheapflights users on 11/3. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/207:57 pmSTL - MIA
2 stops18h 28mFrontier
Sun 11/237:12 amMIA - STL
1 stop11h 31mFrontier
Deal found 11/3$226
This Kiwi.com deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/197:45 pmSTL - MIA
2 stops14h 38mMultiple Airlines
Thu 11/275:30 amMIA - STL
1 stop9h 59mMultiple Airlines
Deal found 11/2$227
This Frontier deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/17:43 pmSTL - MIA
1 stop8h 27mFrontier
Thu 12/115:30 amMIA - STL
1 stop6h 37mFrontier
Deal found 11/2$230
This Kiwi.com deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sat 12/137:43 pmSTL - MIA
2 stops14h 05mFrontier
Sat 12/2010:19 pmMIA - STL
1 stop12h 21mFrontier
Deal found 11/2$231
This Kiwi.com deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 11/177:45 pmSTL - MIA
2 stops16h 43mFrontier
Thu 11/275:30 amMIA - STL
1 stop9h 59mFrontier
Deal found 11/2$232
This Kiwi.com deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Wed 11/267:03 pmSTL - MIA
2 stops21h 06mFrontier
Wed 12/33:13 pmMIA - STL
1 stop20h 54mFrontier
Deal found 11/2$235
This Kiwi.com deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/123:30 pmSTL - MIA
2 stops40h 52mFrontier
Tue 12/235:30 amMIA - STL
1 stop5h 10mFrontier
Deal found 11/2$236
This Kiwi.com deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Sun 11/303:14 pmSTL - MIA
1 stop18h 35mFrontier
Sun 12/75:30 amMIA - STL
1 stop5h 17mFrontier
Deal found 11/2$237
This Frontier deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Frontier is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Fri 12/127:43 pmSTL - MIA
1 stop8h 36mFrontier
Sun 12/215:30 amMIA - STL
1 stop5h 10mFrontier
Deal found 11/2$238
This Kiwi.com deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/277:57 pmSTL - MIA
2 stops19h 30mFrontier
Sun 12/75:30 amMIA - STL
1 stop5h 17mFrontier
Deal found 11/2$241
This Kiwi.com deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Mon 12/17:03 pmSTL - MIA
1 stop19h 54mMultiple Airlines
Sat 12/66:53 pmMIA - STL
1 stop15h 54mMultiple Airlines
Deal found 11/2$244
This Kiwi.com deal was found by Cheapflights users on 11/2. Clicking the “Pick Dates” button in this card will allow you to select your dates and further customize your flight criteria. From there, click “Find deals”, make sure Kiwi.com is selected, and click “Compare selected” under the list of providers to see comparable flight deals.
Thu 11/132:12 pmSTL - MIA
2 stops18h 59mFrontier
Sat 11/156:35 pmMIA - STL
1 stop16h 37mFrontier
Deal found 11/2$245

Cheap flight deals from St. Louis to Key Largo

Keep the following information in mind while searching for St. Louis to Key Largo flight deals. Data was last updated November 3, 2025.

Most accurate provider

eDreams
3 stars

Most trusted provider

eDreams
3 stars

Round-trip from

$226
(Kiwi.com)

One-way from

$55
(Priceline)

Popular in

March

Cheapest in

September

Average price

$419
Provider with most accurate pricing for Lambert-St Louis-Miami flight deals.
Search Deals
Provider most trusted by Cheapflights users for Lambert-St Louis-Miami flights.
Search Deals
From Lambert-St Louis to Key Largo
Search Deals
One-way flight from Lambert-St Louis to Key Largo
Search Deals
Highest demand for flights based on searches. 9% potential increase in price ($43 potential increase over avg. RT price).
Search Deals
Cheapest flight prices on average. 2% potential price decrease ($12 potential savings vs. average RT price).
Search Deals
Average for round-trip flights in November 2025
Search Deals

Cheapflights Fare Finder

 
Customize your flight search to find flights from St. Louis to Key Largo that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated November 3, 2025.
Use the filters below to find and compare flights from St. Louis to Key Largo that are best for you.

Fly from

St. Louis

Fly to

Key Largo

Route

Depart

Return

Price

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Fri 1/30

6:57 pm-12:51 am

1 stop4h 54m

Miami

Sat 2/7

8:15 am-11:56 am

1 stop4h 41m

$339

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Mon 12/8

11:40 am-5:25 pm

1 stop4h 45m

Miami

Wed 12/17

12:36 pm-4:21 pm

1 stop4h 45m

$339

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Fri 1/23

6:02 pm-10:00 pm

Nonstop2h 58m

Miami

Mon 1/26

3:19 pm-5:22 pm

Nonstop3h 03m

$341

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Fri 2/6

1:40 pm-10:25 pm

1 stop7h 45m

Miami

Sun 2/15

6:30 am-2:10 pm

2 stops8h 40m

$344

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Fri 1/23

6:57 pm-12:51 am

1 stop4h 54m

Miami

Mon 1/26

7:25 pm-11:39 pm

1 stop5h 14m

$369

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Fri 11/28

3:45 pm-10:05 pm

1 stop5h 20m

Miami

Sat 12/6

10:45 am-12:55 pm

Nonstop3h 10m

$385

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Sun 1/11

6:00 am-2:16 pm

1 stop7h 16m

Miami

Mon 1/12

6:00 am-11:05 am

1 stop6h 05m

$404

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Wed 11/26

3:05 pm-10:55 pm

2 stops6h 50m

Miami

Wed 12/3

9:30 am-5:20 pm

2 stops8h 50m

$405

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Thu 1/15

6:25 am-5:10 pm

2 stops9h 45m

Miami

Mon 1/19

6:30 am-2:10 pm

2 stops8h 40m

$406

St. LouisMiami

STL - MIA

STLMIA

Lambert-St Louis

Thu 12/11

12:04 pm-12:46 am

1 stop11h 42m

$61

Flights are sorted by cheapest round-trip flights first.

Deals found on 11/2

Showing 1-10 of 21 results
1
2
3

Best time to book a flight from St. Louis to Key Largo

Have a flexible travel schedule? Discover the best time to fly to Key Largo from St. Louis with our price prediction graph.
Estimated round-trip price
Rates are based on past data. Find the cheapest month and day to book your flight based on your travel requirements, then search for cheap deals.

Cheapflights Insights

Everything you need to know about your flight from St. Louis to Key Largo

How far ahead should I book a flight from St. Louis to Key Largo?

Use this chart to determine the optimal time to book a round-trip flight from St. Louis to Key Largo. Price data was last updated on October 31, 2025.

To ensure you get the cheapest price possible for a flight from St. Louis to Key Largo, you should look to book at least 33 days in advance of your intended travel date. The price of your flight may increase if you delay and leave booking until a week or so before departure.

What is the cheapest month to book a flight from St. Louis to Key Largo?

Currently, February is the cheapest month in which you can book a flight from St. Louis to Key Largo (average of $68). Flying from St. Louis to Key Largo in June is currently the most expensive (average of $124). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

What is the cheapest time of day to fly from STL to KE9?

Find hourly flight availability from St. Louis to Key Largo. Discover flight options and departure times throughout the day, allowing you to choose a departure time that suits your schedule. Data last updated November 3, 2025.

It’s optimal to fly from St. Louis to Key Largo in the evening. By choosing this option you can save up to 23% on the cost of your flight, compared to a flight at noon.

What is the cheapest day to fly from St. Louis to Key Largo?

Use this chart to determine the cheapest time to fly round-trip from St. Louis to Key Largo. Price data was last updated on December 16, 2024.

Travelers seeking maximum savings on their St. Louis to Key Largo flight should consider departing on Tuesday evenings when fares are most often at their lowest. Monday at noon flights should be avoided if possible as fares are typically the most expensive at this time.

Weekly flight availability from St. Louis to Key Largo

Explore weekly flight availability from St. Louis to Key Largo. Discover flights operating on different days of the week, giving you the flexibility to choose a travel day that best fits your plans. Compare info to find the most convenient option for your journey. Data last updated November 3, 2025.

The most flights from STL to KE9 are scheduled on a Friday (5 on average). You will have fewer flight options on Tuesday, which is when the least amount of flights are scheduled (3 on average).

Reviews of airlines servicing Key Largo

Get insights into the airlines that provide service to Key Largo. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to Key Largo. Reviews last updated November 3, 2025.
Peruse reviews from past customers who have flown with Southwest, Delta, and American Airlines from St. Louis to Key Largo to help guide your decision. You can also see how each airline stacks up in terms of entertainment options, comfort, food, crew/service, and boarding process.
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Boarding

8.1

Crew

8.6

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Southwest
8.0
Very good
4,238 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Boarding

8.1

Crew

8.6

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Delta
7.9
Good
8,002 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Boarding

8.1

Crew

8.6

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
American Airlines
7.2
Good
11,038 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Boarding

8.1

Crew

8.6

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Spirit Airlines
6.3
Okay
8,115 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Boarding

8.1

Crew

8.6

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines
Frontier
5.8
Fair
3,117 reviews
Southwest
8.0
Very good
4,238 reviews

Comfort

8.0

Entertainment

7.5

Food

7.0

Boarding

8.1

Crew

8.6

Overall

8.0

Reviews

1 / 20
2.0
Mediocre

Mike,Aug 2025

OKC - AUS

AC was not adequate, even on a night flight. WiFi subpar even for the airlines

Related info for your journey

Find useful and relevant information for your journey from St. Louis to Key Largo. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • What airport do you fly from for flights from St. Louis to Key Largo?

    For a flight from St. Louis to Key Largo, you will be flying from Lambert-St Louis. Lambert-St Louis (STL) is just 12.7 mi from the center of the city. Lambert-St Louis is the only St. Louis airport and it handles 4 outbound flights to Key Largo per day. 6 airlines have flights to Key Largo from Lambert-St Louis on a regular basis.

  • How popular is this St. Louis to Key Largo flight route?

    The Lambert-St Louis to Key Largo flight path was viewed by 56 users in the past month. Keep an eye out for changes in search interest prior to high and low season.

  • How long is the flight from St. Louis to Key Largo?

    For as low as $341, Delta can have you in Key Largo from St. Louis in 2h 58m. The distance between St. Louis and Key Largo is about 1069 mi. Both multi-stop and nonstop flights can be found to your destination and back.

  • What are the most reliable airlines from St. Louis to Key Largo?

    The top 3 most reliable airlines when flying from St. Louis to Key Largo are Qatar Airways (86%), Southwest (80%) and American Airlines (74%).

  • What are the cheapest flights from St. Louis to Key Largo?

    On average you can expect to pay $402 for a flight from St. Louis to Key Largo. The cheapest flight overall is $56 while the most popular route, (Lambert-St Louis - Miami) is currently priced at $170.

  • Can I find deals for flights from St. Louis to Key Largo that include hotel bookings?

    Yes. In addition to deals on St. Louis to Key Largo flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from St. Louis to Key Largo?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from St. Louis to Key Largo.

  • Can I find deals for business class flights from St. Louis to Key Largo?

    Yes. Cheapflights offers flight deals from St. Louis to Key Largo by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • What is the cheapest month to book a flight from St. Louis to Key Largo?

    Currently, February is the cheapest month in which you can book a flight from St. Louis to Key Largo (average of $68). Flying from St. Louis to Key Largo in June is currently the most expensive (average of $124). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

See more FAQs

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for St. Louis to Key Largo

See prices for flight routes from nearby airports that may be better suited for you.
St. Louis to Orlando flights
Kansas City to Orlando flights
St. Louis to Miami flights
Kansas City to Miami flights
Kansas City to Tampa flights
St. Louis to Tampa flights
Kansas City to Fort Lauderdale flights
St. Louis to Fort Lauderdale flights
Springfield to Orlando flights
St. Louis to Key West flights
St. Louis to Fort Myers flights
Kansas City to Fort Myers flights
St. Louis to Sarasota flights
Kansas City to Jacksonville flights
Springfield to Miami flights
Kansas City to Pensacola flights
St. Louis to Pensacola flights
St. Louis to Jacksonville flights
Kansas City to West Palm Beach flights
Kansas City to Key West flights
Springfield to Fort Lauderdale flights
Kansas City to Sarasota flights
St. Louis to West Palm Beach flights
St. Louis to Panama City flights
Springfield to Tampa flights
Kansas City to Panama City flights
St. Louis to Daytona Beach flights
Kansas City to Valparaiso flights
Springfield to Melbourne flights
Kansas City to Tallahassee flights
St. Louis to Melbourne flights
Springfield to West Palm Beach flights
Kansas City to St Petersburg flights
Springfield to Daytona Beach flights
Springfield to Pensacola flights
Columbia to Orlando flights
Springfield to Key West flights
St. Louis to Tallahassee flights
Springfield to Sarasota flights
St. Louis to Valparaiso flights
Columbia to Miami flights
St. Louis to Valdosta flights
Kansas City to Orlando Sanford Intl flights
Kansas City to Daytona Beach flights
Springfield to Panama City flights
St. Louis to Gainesville flights
Joplin to Orlando flights
Joplin to Pensacola flights
Joplin to Fort Lauderdale flights
Springfield to Fort Myers flights

Top 6 airlines flying from St. Louis to Key Largo

Discover the top 6 airlines that operate flights from St. Louis to Key Largo. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 2,558,603 searches. Data last updated November 3, 2025.
AirlineCheapestAverageFlexibilityOn-time
Spirit AirlinesCheapest$68Average$153FlexibilityNo cancel feeOn-time65%
FrontierCheapest$142Average$227FlexibilityNo cancel feeOn-time62%
United AirlinesCheapest$150Average$475FlexibilityNo cancel feeOn-time69%
DeltaCheapest$172Average$408FlexibilityNo cancel feeOn-timeN/A
American AirlinesCheapest$226Average$425FlexibilityNo cancel feeOn-time71%
SouthwestCheapest$237Average$456FlexibilityNo cancel feeOn-time63%

100% Free

Cheapflights is completely free to use, so you can start saving the moment you arrive.

Book with Flexibility

Our users can plan ahead with confidence and find flights with no change fees

Travel Smart

Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.