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Cheap flights from London Heathrow Airport to Siem Reap from £349

LHR — SAI
29 Nov — 6 Dec1
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

Tue 10/1121:00 -
2 stops40h 05m
Sat 5/1221:05 -
2 stops51h 25m
Deal found 29/10£624
Thu 3/1212:30 -
2 stops48h 35m
Thu 17/1221:05 -
2 stops40h 20m
Deal found 26/10£624
Sun 29/1121:00 -
2 stops40h 05m
Sun 6/1221:05 -
2 stops27h 25m
Deal found 30/10£633
Sun 15/1121:00 -
2 stops40h 05m
Sun 6/1221:05 -
3 stops51h 25m
Deal found 27/10£651
Sat 14/1121:00 -
3 stops64h 05m
Sun 29/1121:05 -
3 stops40h 20m
Deal found 26/10£651
Thu 3/1207:40 -
2 stops27h 50m
Wed 16/1209:55 -
2 stops18h 45m
Deal found 25/10£672
Sun 15/1121:00 -
2 stops40h 05m
Sun 29/1121:05 -
2 stops27h 25m
Deal found 26/10£679
Thu 3/1209:00 -
2 stops26h 30m
Wed 16/1209:55 -
2 stops34h 05m
Deal found 26/10£687
Tue 10/1121:00 -
2 stops40h 05m
Thu 3/1221:05 -
2 stops40h 20m
Deal found 28/10£691

Find flight deals from Heathrow to Siem Reap

Round-trip from

£624

One-way from

£349

Popular in

December

Cheapest in

July

Average price

£767
China Eastern
  • China Eastern
  • 10/11-5/12
  • 4 total stops
  • 91h 30m total
  • London to Siem Reap
Search Deals
24/1-31/12
  • 24/1-31/12
  • 3 total stops
  • 28h 00m total
  • London to Siem Reap
Search Deals
Highest demand for flights based on searches. 7% potential increase in price (£50 potential increase over avg. return price).
Search Deals
Cheapest flight prices on average. 3% potential price decrease (£22 potential savings vs. average return price).
Search Deals
Average for round-trip flights in October 2026
Search Deals

Cheapflights Fare Finder

 
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

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Thu 12/11

22:30-16:55

2 stops35h 25m

Siem Reap–Angkor Intl

Wed 31/12

00:00-18:00

Nonstop0h 00m

£393

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Mon 9/11

21:10-16:05

3 stops35h 55m

Siem Reap–Angkor Intl

Wed 31/12

00:00-18:00

Nonstop0h 00m

£403
Fastest return journey

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Sat 28/11

12:30-20:05

2 stops24h 35m

Siem Reap–Angkor Intl

Wed 31/12

00:00-18:00

Nonstop0h 00m

£429

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Tue 10/11

21:00-14:15

3 stops34h 15m

Siem Reap–Angkor Intl

Wed 31/12

00:00-18:00

Nonstop0h 00m

£429

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Wed 9/12

13:45-08:45

3 stops36h 00m

Siem Reap–Angkor Intl

Wed 31/12

00:00-18:00

Nonstop0h 00m

£443

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Sat 28/11

11:00-21:45

1 stop27h 45m

Siem Reap–Angkor Intl

Wed 31/12

00:00-18:00

Nonstop0h 00m

£474

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Mon 4/1

22:00-08:55

2 stops27h 55m

Siem Reap–Angkor Intl

Wed 31/12

00:00-18:00

Nonstop0h 00m

£488

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Thu 10/12

07:30-17:40

2 stops27h 10m

Siem Reap–Angkor Intl

Wed 31/12

00:00-18:00

Nonstop0h 00m

£495

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Thu 3/12

07:40-18:30

2 stops27h 50m

Siem Reap–Angkor Intl

Mon 14/12

09:55-08:05

2 stops29h 10m

£696

LondonSiem Reap

LHR London Heathrow - SAI Siem Reap–Angkor Intl

LHRSAI

London Heathrow

Thu 3/12

13:45-18:30

2 stops21h 45m

Siem Reap–Angkor Intl

Sat 12/12

09:55-21:40

2 stops18h 45m

£745

Flights are sorted by cheapest return flights first.

Deals found on 30/10

Showing 1-10 of 16 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

Cheapflights Insights

Everything you need to know about your flight from London Heathrow Airport to Siem Reap

What is the cheapest month to book a flight from London Heathrow Airport to Region of Siem Reap?

Currently, March is the cheapest month in which you can book a flight from London Heathrow Airport to Region of Siem Reap (average of £693). Flying from London Heathrow Airport to Region of Siem Reap in October is currently the most expensive (average of £1,156). 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.

How much does it cost for a return flight from London Heathrow Airport to Region of Siem Reap?

Airfare is below average for this route at the moment.
London Heathrow Airport to Region of Siem Reap flights typically cost between £750 and £1,001 in November.
The cheapest return price found within the last 5 days was £624 on China Eastern (10 Nov–3 Dec).

Reviews of airlines servicing Siem Reap

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
1,631 reviews
Check prices

Entertainment

8.1

Overall

8.2

Crew

8.6

Boarding

8.3

Comfort

8.0

Food

7.8

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
1,631 reviews
Singapore Airlines
8.2
Very Good
1,631 reviews
Check prices

Entertainment

8.1

Overall

8.2

Crew

8.6

Boarding

8.3

Comfort

8.0

Food

7.8

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
433 reviews
Singapore Airlines
8.2
Very Good
1,631 reviews
Check prices

Entertainment

8.1

Overall

8.2

Crew

8.6

Boarding

8.3

Comfort

8.0

Food

7.8

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
294 reviews
Singapore Airlines
8.2
Very Good
1,631 reviews
Check prices

Entertainment

8.1

Overall

8.2

Crew

8.6

Boarding

8.3

Comfort

8.0

Food

7.8

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

  • 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 26h 30m. Vietnam Airlines provides one of the quickest options available for as low as £778. Airlines will cover a distance of 6106 mi.

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

    £381 is the cheapest one-way deal found within the past few days, from Austrian Airlines. You may also be able to find cheap deals on Vietnam Airlines and Singapore Airlines, with prices starting from £455 and £508, 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.

  • What is the cheapest month to book a flight from London Heathrow Airport to Region of Siem Reap?

    Currently, March is the cheapest month in which you can book a flight from London Heathrow Airport to Region of Siem Reap (average of £693). Flying from London Heathrow Airport to Region of Siem Reap in October is currently the most expensive (average of £1,156). 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

Top 3 airlines flying from Heathrow to Siem Reap

AirlineCheapestAverageFlexibilityOn-time
Singapore AirlinesCheapest£669Average£810FlexibilityNo cancel feeOn-time81%
Search Singapore Airlines flights
Vietnam AirlinesCheapest£748Average£822FlexibilityNo cancel feeOn-time81%
Search Vietnam Airlines flights
Thai AirwaysCheapest£896Average£1,006FlexibilityNo cancel feeOn-time77%
Search Thai Airways flights

Fly with Cheapflights

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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