Are there nonstop flights from London (LHR) to Phnom Penh (KTI)?

No. The fastest connection is via Bangkok, about 12h 53m of total flying time.

What is the fastest connection from London (LHR) to Phnom Penh (KTI)?

via Bangkok ≈ 12h 53m, via New Delhi ≈ 13h, via Hanoi ≈ 13h 10m (estimated flying time, excluding layovers).

from 29,500 ANA miles, from 40,000 JAL miles (economy, one way, based on the published award charts).

London Heathrow Airport (LHR) to Techo International Airport (KTI)・10,058 km

No nonstop flights. The fastest connection is via Bangkok (BKK), about 12h 53m of flying time (layover not included).

With milesANA 29,500 miles+ (via BKK)JAL 40,000 miles+ (via DOH)Economy, one way, estimate. Tap a connection for miles by cabin.

None.

26 one-stop options, sorted by estimated flying time. Tap one to see the airlines on each leg and booking links.

Times are estimated from distance. Check schedules, frequency and availability with the airline or a booking site.