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Cheap flights from London Heathrow Airport to Siem Reap from £352

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 4/9. Fares are subject to change and may not be available on all flights or dates of travel.
LHR — SAI
29 Aug — 5 Sep1
1 adult
1 adult, Economy, 0 bags

Cheap flight deals from Heathrow to Siem Reap

Enter your travel dates to find the best prices.

Cheapest flights from Heathrow to Siem Reap
Explore the most affordable flight options available from Heathrow to Siem Reap. Find the lowest fares from popular airlines and budget airlines, with prices last updated on 30 July 2026.

Wed 2/912:10
LHR
-
SAI
2 stops24h 45m
Multiple Airlines
Wed 30/919:35
SAI
-
LHR
2 stops18h 40m
Multiple Airlines
Deal found 26/7£593
Mon 14/908:40
LHR
-
SAI
2 stops28h 15m
SWISS
Sun 27/909:40
SAI
-
LHR
2 stops28h 15m
SWISS
Deal found 26/7£599
Wed 2/912:10
LHR
-
SAI
2 stops24h 45m
SWISS
Thu 1/1009:40
SAI
-
LHR
2 stops28h 15m
SWISS
Deal found 26/7£615
Mon 21/908:40
LHR
-
SAI
2 stops28h 15m
Multiple Airlines
Fri 25/919:35
SAI
-
LHR
2 stops18h 40m
Multiple Airlines
Deal found 25/7£618
Wed 9/906:00
LHR
-
SAI
2 stops30h 55m
SWISS
Tue 22/909:40
SAI
-
LHR
2 stops18h 05m
SWISS
Deal found 25/7£629
Wed 2/912:10
LHR
-
SAI
2 stops24h 45m
SWISS
Tue 29/909:40
SAI
-
LHR
2 stops18h 05m
SWISS
Deal found 26/7£630
Wed 2/912:10
LHR
-
SAI
2 stops24h 45m
SWISS
Wed 23/909:40
SAI
-
LHR
2 stops36h 45m
SWISS
Deal found 29/7£632
Wed 30/906:00
LHR
-
SAI
2 stops30h 55m
Austrian Airlines
Wed 21/1019:35
SAI
-
LHR
2 stops18h 45m
Austrian Airlines
Deal found 27/7£639
Thu 19/1106:35
LHR
-
SAI
2 stops20h 15m
Multiple Airlines
Thu 3/1209:55
SAI
-
LHR
2 stops18h 45m
Multiple Airlines
Deal found 28/7£648

Find flight deals from Heathrow to Siem Reap

Keep the following information in mind while searching for Heathrow to Siem Reap flight deals. Data was last updated 30 July 2026.

Round-trip from

£593

One-way from

£352

Popular in

December

Cheapest in

July

Average price

£629
Lufthansa
  • Lufthansa
  • 2/9-30/9
  • 4 total stops
  • 43h 25m total
  • London to Siem Reap
Search Deals
4/9
  • 4/9
  • 3 total stops
  • 38h 20m total
  • London to Siem Reap
Search Deals
Highest demand for flights based on searches. 11% potential increase in price (£75 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 4% potential price decrease (£28 potential savings vs. average return price).
Search Deals
Average for round-trip flights in July 2026
Search Deals

Cheapflights Fare Finder

 
Customise your flight search to find flights from Heathrow to Siem Reap 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 858,174 searches. Data last updated 30 July 2026.
Use the filters below to find and compare flights from London Heathrow Airport to Siem Reap that are best for you.

Fly from

Fly to

Route

Depart

Return

Price

Cheapest return flight
Fastest return journey

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Thu 3/9

19:30-18:55

2 stops17h 25m

Siem Reap–Angkor Intl

Tue 29/9

09:40-21:45

2 stops18h 05m

£693

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Wed 11/11

06:00-09:50

2 stops20h 50m

Siem Reap–Angkor Intl

Mon 23/11

09:55-21:40

2 stops18h 45m

£743

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Wed 4/11

15:50-21:10

2 stops22h 20m

Siem Reap–Angkor Intl

Wed 18/11

13:20-11:40

2 stops29h 20m

£834

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Thu 3/12

11:00-17:40

1 stop23h 40m

Siem Reap–Angkor Intl

Mon 14/12

18:40-07:15

1 stop19h 35m

£860

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Sun 8/11

08:50-12:40

2 stops20h 50m

Siem Reap–Angkor Intl

Mon 23/11

09:55-06:40

2 stops27h 45m

£932

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Tue 10/11

11:00-17:40

1 stop23h 40m

Siem Reap–Angkor Intl

Sat 5/12

21:30-07:15

2 stops40h 45m

£934

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Tue 10/11

06:20-17:40

2 stops28h 20m

Siem Reap–Angkor Intl

Thu 3/12

17:55-07:15

1 stop20h 20m

£964

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Thu 3/12

11:00-17:40

1 stop23h 40m

Siem Reap–Angkor Intl

Mon 14/12

17:55-08:20

2 stops21h 25m

£985
Cheapest one-way

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Wed 9/9

09:55-09:15

3 stops41h 20m

£355

LondonSiem Reap

LHR - SAI

LHRSAI

London Heathrow

Fri 6/11

13:45-09:20

3 stops36h 35m

£434

Flights are sorted by cheapest return flights first.

Deals found on 28/7

Showing 1-10 of 18 resultsSorted by cheapest first
1
2

Best time to book a flight from Heathrow to Siem Reap

Have a flexible travel schedule? Discover the best time to fly to Siem Reap from Heathrow with our price prediction graph.
Estimated return 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 London Heathrow Airport to Siem Reap

No data available for this route at this time. Please check back soon.

Reviews of airlines servicing Siem Reap

Get insights into the airlines that provide service to Siem Reap. 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 Siem Reap. Reviews last updated 30 July 2026.
Get a feel of what it's like to fly with Singapore Airlines,Thai Airways, andVietnam Airlines from London Heathrow Airport to Siem Reap by reading reviews from past customers. You can also see how each airline compares in terms of entertainment options, comfort, food, crew/service, and boarding process.
Singapore Airlines
8.2
Very Good
1,584 reviews
Check prices

Entertainment

8.1

Overall

8.2

Comfort

8.0

Boarding

8.3

Food

7.8

Crew

8.6

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.
Singapore Airlines
8.2
Very Good
1,584 reviews
Singapore Airlines
8.2
Very Good
1,584 reviews
Check prices

Entertainment

8.1

Overall

8.2

Comfort

8.0

Boarding

8.3

Food

7.8

Crew

8.6

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.
Thai Airways
7.9
Good
412 reviews
Singapore Airlines
8.2
Very Good
1,584 reviews
Check prices

Entertainment

8.1

Overall

8.2

Comfort

8.0

Boarding

8.3

Food

7.8

Crew

8.6

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.
Vietnam Airlines
7.7
Good
280 reviews
Singapore Airlines
8.2
Very Good
1,584 reviews
Check prices

Entertainment

8.1

Overall

8.2

Comfort

8.0

Boarding

8.3

Food

7.8

Crew

8.6

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.
Austrian Airlines
7.6
Good
950 reviews
Singapore Airlines
8.2
Very Good
1,584 reviews
Check prices

Entertainment

8.1

Overall

8.2

Comfort

8.0

Boarding

8.3

Food

7.8

Crew

8.6

Reviews

1 / 20
6.0
Good

Anonymous,Feb 2026

SAI - SIN

The only issue we had was seat selection. Was not easy to change, after they assigned seats. Also, the premium economy seats, are nothing special.. All and all safe flight with minor back issues.

Related info for your journey

Find useful and relevant information for your journey from Heathrow to Siem Reap. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.

  • How long is the flight from London Heathrow Airport to Region of Siem Reap?

    A quick flight from London Heathrow Airport to Region of Siem Reap can take about 22h 20m. Emirates provides one of the quickest options available for as low as £834. Airlines will cover a distance of 6106 mi. When browsing for deals, the options you’ll see will be for both direct flights and flights with stops.

  • What are the cheapest airlines to fly from London Heathrow Airport to Region of Siem Reap one-way?

    £456 is the cheapest one-way deal found within the past few days, from Vietnam Airlines. You may also be able to find cheap deals on Singapore Airlines and Thai Airways, with prices starting from £520 and £564, respectively.

  • Can I find deals for flights from Heathrow to Siem Reap that include hotel bookings?

    Yes. In addition to deals on Heathrow to Siem Reap flights, Cheapflights offers holiday packages that include both flights and hotel.

  • How can I find direct flights from Heathrow to Siem Reap?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Heathrow to Siem Reap.

  • Can I find deals for business class flights from Heathrow to Siem Reap?

    Yes. Cheapflights offers flight deals from Heathrow to Siem Reap by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

See more FAQs

Browse thousands of different options on Cheapflights for your next trip

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Top 4 airlines flying from Heathrow to Siem Reap

Discover the top 4 airlines that operate flights from Heathrow to Siem Reap. 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 858,174 searches. Data last updated 30 July 2026.
AirlineCheapestAverageFlexibilityOn-time
Austrian AirlinesCheapest£544Average£694FlexibilityNo cancel feeOn-time78%
Search Austrian Airlines flights
Vietnam AirlinesCheapest£622Average£823FlexibilityNo cancel feeOn-time81%
Search Vietnam Airlines flights
Singapore AirlinesCheapest£670Average£781FlexibilityNo cancel feeOn-time81%
Search Singapore Airlines flights
Thai AirwaysCheapest£897Average£1,009FlexibilityNo cancel feeOn-time77%
Search Thai Airways flights

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travellers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Heathrow to Siem Reap?

Cheapflights goes through 900+ travel sites to look for the best flight deals for flights from Heathrow to Siem Reap. Too many options? Cheapflights also provides filters for things like airlines, price ranges, and number of stops to help you make a decision easily.

Why should you use Cheapflights to find cheap flight tickets from Heathrow to Siem Reap?

Cheapflights helps you find that perfect flight to Siem Reap from Heathrow by searching from hundreds of airlines and agencies you know and love. We are also free to use, in case you were wondering!

Can Cheapflights find flights from Heathrow to Siem Reap with no change fees?

Certainly. Search results for flights to Siem Reap from Heathrow shown to you on Cheapflights can be narrowed down with different useful search filters, which includes flexible booking options.

Can Cheapflights notify me if prices for flights from Heathrow to Siem Reap become cheaper?

Yes, Cheapflights offers price alerts on Heathrow to Siem Reap flights so you can book your travel at the perfect time. Price Alerts can be enabled by clicking the bell icon next to the flight deals above and providing your email address where you want to receive the alerts.

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