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Cheap flights from Seattle to Illinois from $65

This is the cheapest one-way flight price found by a momondo user in the last 72 hours by searching for a flight from Seattle to Illinois departing on 4/24. Fares may change, and may not be available for all flights or travel dates. Click the price to refresh the search for this deal.
1 adult
0 bags

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Find the cheapest flights from Seattle to Illinois

Cheap round-trip flights

Enter your travel dates to find the best prices.
Frontier Logo
7:12 pm - 7:32 pm
SEA
-
STL
22h 20m
1 stop
Frontier Logo
8:17 pm - 9:27 am
STL
-
SEA
15h 10m
1 stop
$133Frontier
Fri, Apr 24 - Mon, Apr 27
Frontier Logo
7:12 pm - 7:32 pm
SEA
-
STL
22h 20m
1 stop
Frontier Logo
8:06 pm - 9:52 am
STL
-
SEA
15h 46m
1 stop
$138Frontier
Fri, Apr 17 - Thu, Apr 30
Frontier Logo
6:57 pm - 7:12 pm
SEA
-
STL
22h 15m
1 stop
Frontier Logo
8:12 pm - 9:27 am
STL
-
SEA
15h 15m
1 stop
$148Frontier
Fri, May 8 - Mon, May 11
Delta Logo
5:35 am - 1:23 pm
SEA
-
STL
5h 48m
1 stop
Delta Logo
5:00 pm - 10:01 pm
STL
-
SEA
7h 01m
1 stop
$177Delta
Tue, Apr 28 - Sat, May 2
United Airlines Logo
7:00 am - 1:12 pm
SEA
-
ORD
4h 12mnonstop
United Airlines Logo
7:40 am - 2:46 pm
ORD
-
SEA
9h 06m
1 stop
$185United Airlines
Sat, Apr 18 - Tue, Apr 21
Alaska Airlines Logo
1:28 pm - 7:52 pm
SEA
-
ORD
4h 24mnonstop
Alaska Airlines Logo
8:48 pm - 11:29 pm
ORD
-
SEA
4h 41mnonstop
$193Alaska Airlines
Fri, May 1 - Thu, May 7
Delta Logo
7:15 am - 1:23 pm
SEA
-
ORD
4h 08mnonstop
Delta Logo
6:00 pm - 8:43 pm
ORD
-
SEA
4h 43mnonstop
$197Delta
Fri, May 1 - Mon, May 4
American Airlines Logo
12:13 am - 9:22 am
SEA
-
CMI
7h 09m
1 stop
American Airlines Logo
3:47 pm - 11:04 pm
CMI
-
SEA
9h 17m
1 stop
$268American Airlines
Thu, Mar 26 - Tue, Mar 31
United Airlines Logo
10:40 pm - 8:54 am
SEA
-
CMI
8h 14m
1 stop
United Airlines Logo
1:32 pm - 10:18 pm
CMI
-
SEA
10h 46m
2 stops
$274United Airlines
Mon, Jul 27 - Mon, Aug 31
American Airlines Logo
3:17 pm - 11:54 pm
SEA
-
MLI
6h 37m
1 stop
American Airlines Logo
6:41 pm - 12:36 am
MLI
-
SEA
7h 55m
1 stop
$334American Airlines
Thu, Apr 9 - Mon, Apr 13

Delta flights from Seattle to Illinois

Our best Delta deals on Seattle to Illinois flight tickets
Delta
Apr 28
SEA5:35 amSeattle/Tacoma Intl
5h 48m
1 stop
STL1:23 pmLambert-St Louis
Apr 28
STL6:45 pmLambert-St Louis
7h 14m
1 stop
SEA11:59 pmSeattle/Tacoma Intl
$177
Delta
Apr 17
SEA1:30 pmSeattle/Tacoma Intl
8h 55m
1 stop
STL12:25 amLambert-St Louis
Apr 29
STL2:20 pmLambert-St Louis
6h 10m
1 stop
SEA6:30 pmSeattle/Tacoma Intl
$185
Delta
Mar 27
SEA1:32 pmSeattle/Tacoma Intl
8h 49m
1 stop
STL12:21 amLambert-St Louis
Apr 8
STL6:12 pmLambert-St Louis
7h 51m
1 stop
SEA12:03 amSeattle/Tacoma Intl
$193

Alaska Airlines flights from Seattle to Illinois

Our best Alaska Airlines deals on Seattle to Illinois flight tickets
Alaska Airlines
Mar 24
SEA6:02 pmSeattle/Tacoma Intl
3h 57m
STL11:59 pmLambert-St Louis
Mar 25
STL7:00 amLambert-St Louis
4h 35m
SEA9:35 amSeattle/Tacoma Intl
$207
Alaska Airlines
Apr 8
SEA6:02 pmSeattle/Tacoma Intl
3h 57m
STL11:59 pmLambert-St Louis
Apr 22
STL7:00 amLambert-St Louis
4h 32m
SEA9:32 amSeattle/Tacoma Intl
$217
Alaska Airlines
May 20
SEA12:45 pmSeattle/Tacoma Intl
4h 00m
STL6:45 pmLambert-St Louis
May 27
STL7:41 pmLambert-St Louis
4h 31m
SEA10:12 pmSeattle/Tacoma Intl
$227

momondo Fare Finder

 
Customize your flight search to find flights from Seattle to Illinois 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, momondo users made 832,500 searches. Data last updated February 25, 2026.
Use the filters below to find and compare flights from Seattle to Illinois that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 4/24

7:12 pm-7:32 pm

1 stop22h 20m

Lambert-St Louis

Mon 4/27

8:17 pm-9:27 am

1 stop15h 10m

$133

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 4/17

7:12 pm-7:32 pm

1 stop22h 20m

Lambert-St Louis

Thu 4/30

8:06 pm-9:52 am

1 stop15h 46m

$138

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Fri 5/8

6:57 pm-7:12 pm

1 stop22h 15m

Lambert-St Louis

Mon 5/11

8:12 pm-9:27 am

1 stop15h 15m

$148

SeattleSt. Louis

SEA - STL

SEASTL

Seattle/Tacoma Intl

Tue 4/28

5:35 am-1:23 pm

1 stop5h 48m

Lambert-St Louis

Sat 5/2

5:00 pm-10:01 pm

1 stop7h 01m

$177

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

Sat 4/18

7:00 am-1:12 pm

Nonstop4h 12m

Chicago O'Hare Intl

Tue 4/21

7:40 am-2:46 pm

1 stop9h 06m

$185

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

Fri 5/1

1:28 pm-7:52 pm

Nonstop4h 24m

Chicago O'Hare Intl

Thu 5/7

8:48 pm-11:29 pm

Nonstop4h 41m

$193

SeattleChicago

SEA - ORD

SEAORD

Seattle/Tacoma Intl

Fri 5/1

7:15 am-1:23 pm

Nonstop4h 08m

Chicago O'Hare Intl

Mon 5/4

6:00 pm-8:43 pm

Nonstop4h 43m

$197

SeattleChampaign

SEA - CMI

SEACMI

Seattle/Tacoma Intl

Thu 3/26

12:13 am-9:22 am

1 stop7h 09m

Champaign University-Willard

Tue 3/31

3:47 pm-11:04 pm

1 stop9h 17m

$268

SeattleChampaign

SEA - CMI

SEACMI

Seattle/Tacoma Intl

Mon 7/27

10:40 pm-8:54 am

1 stop8h 14m

Champaign University-Willard

Mon 8/31

1:32 pm-10:18 pm

2 stops10h 46m

$274

SeattleMoline

SEA - MLI

SEAMLI

Seattle/Tacoma Intl

Thu 4/9

3:17 pm-11:54 pm

1 stop6h 37m

Moline Quad-City

Mon 4/13

6:41 pm-12:36 am

1 stop7h 55m

$334

Flights are sorted by cheapest round-trip flights first.

Showing 1-10 of 20 resultsSorted by cheapest first
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See travel insights to Illinois from

How to get the cheapest flight ticket from Seattle to Illinois

Look no further. We've gone through all the searches for this route on momondo so you have the important information and insights to find the cheapest flight ticket for your trip

What is the cheapest month to fly to Illinois?

The cheapest month to fly to Illinois from Seattle is in February. Flight prices, which tend to average around $247, are often lower during this time because this is during the off-season. If you aren’t able to travel to Illinois during the month of February, then flying in January is also cheap. Prices for this month can be found on momondo for an average of $267.

What is the cheapest day to depart on your flight to Illinois?

The cheapest day to depart from Seattle to Illinois is on a Wednesday when prices can be found for as low as $387. Flights from Seattle to Illinois on a Sunday will generally be more expensive and average around $483. Keep in mind that these prices on both days could fluctuate depending on the season and the demand.

What is the cheapest time of day to depart on your flight to Illinois?

Our most recent data shows that the best time of day to fly to Illinois is in the afternoon. Flights from Seattle to Illinois during this time can be as low as $292. Flights in the morning are often more expensive with an average ticket price of $438.

What is the cheapest Seattle/Tacoma Intl to Illinois flight route?

Fly from Seattle/Tacoma Intl to Chicago O'Hare Intl for the best Seattle/Tacoma Intl - Illinois flight prices

How far in advance should I book a flight to Illinois?

You are more likely to see cheaper flights to Illinois from Seattle when booking weeks ahead of your departure date. In general, you can expect to find flights to Illinois for around $298 when searching weeks out. However, flight prices might be lower outside of this timeframe. For example, people recently found flights to Illinois from Seattle for as low as $254 on momondo.

What cabin class options are available on Seattle/Tacoma Intl to Illinois flights?

There are 4 cabin classes available to choose from on Seattle/Tacoma Intl to Illinois flights. Cabin price and availability will vary by airline so perform a search above to find the right deals for you.

Can stopping save me money on Seattle to Illinois flights?

No. A direct flight is the cheapest option for a flight between Seattle to Illinois.

Cheap Seattle to Illinois flight deals and tips

Find info about flight duration, direct flights, and airports for your flight from Seattle to Illinois

Best Price Found

$163

Fastest flight time

3h 50m

Direct flights

Every day

Airports in Illinois

98 airports
The best one-way flight to Illinois from Seattle in the past 72 hours is $163. The best round-trip flight deal from Seattle to Illinois found on momondo in the last 72 hours is $311.
The fastest flight from Seattle to Illinois takes 3h 50m
Direct flights go from Seattle to Illinois every day.
There are 98 airports in Illinois. From Seattle there are direct flights to Chicago O'Hare Intl (ORD), Chicago Midway (MDW), Lambert-St Louis (STL).
Search flight deals

  • When did momondo last update prices for flights from Seattle/Tacoma Intl Airport to Illinois?

    Prices for flights from Seattle/Tacoma Intl Airport to Illinois are updated daily.

  • How many operators does momondo search for flights from Seattle/Tacoma Intl Airport to Illinois?

  • How old do you have to be to fly from Seattle/Tacoma Intl Airport to Illinois?

    The minimum age for a child to fly alone is five, but airlines offering an unaccompanied minor (UNMR) service may have their age restrictions, such as regulations concerning flight duration, timing, and layovers. It is recommended that you verify with the airline you are booking with for travel from Seattle/Tacoma Intl Airport to Illinois.

  • What documentation or ID do you need to fly to Illinois?

    The necessary travel and health documents for your Illinois trip may vary depending on your travel plans and individual circumstances. Generally, you should have various documents, such as a national ID card or driver's license and a passport that is valid for six months beyond your scheduled arrival date. We recommend seeking advice from your airline or a trusted third party, such as IATA.

  • What is the most popular plane model from Seattle to Illinois?

Best airlines flying from Seattle to Illinois

Compare and see reviews for airlines that fly from Seattle to Illinois with momondo
Airline
Rating
Free Cancellation
Price
DeltaPriceFrom $97Free CancellationRating
7.9
8,239 reviews
Search Delta flights
Hawaiian AirlinesPriceFrom $114Free CancellationRating
7.8
2,836 reviews
Search Hawaiian Airlines flights
FrontierPriceFrom $137Free CancellationRating
5.7
3,041 reviews
Search Frontier flights
United AirlinesPriceFrom $156Free CancellationRating
7.4
9,347 reviews
Search United Airlines flights
Alaska AirlinesPriceFrom $169Free CancellationRating
8.0
11,952 reviews
Search Alaska Airlines flights
SouthwestPriceFrom $177Free CancellationRating
8.0
4,299 reviews
Search Southwest flights
American AirlinesPriceFrom $177Free CancellationRating
7.1
11,347 reviews
Search American Airlines flights

Why use momondo?

Why should I use momondo to find a flight deal from Seattle to Illinois?

momondo compares prices from hundreds of airlines and agents so you can find and book the best deal on flights from Seattle to Illinois. Millions of users trust and use momondo every year so you are in good hands.

Can I find flights from Seattle to Illinois with flexible booking policies on momondo?

All flight searches from Seattle to Illinois on momondo can be filtered to show those which offer flexible booking policies.

How can momondo help me find flights from Seattle to Illinois?

Once all potential Seattle to Illinois flight options are in front of you, momondo lets you sort and filter flights based on preferences such as airline, price and flight times amongst many other options.

I’m not ready to book a flight from Seattle to Illinois right now. Can momondo alert me if prices change?

Price alerts on flights to Illinois from Seattle are quick and easy to set up on momondo. Simply perform a search and select the price alert feature. It is as simple as that.

An easier way to manage your Illinois trip

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