Are there nonstop flights from Osaka (KIX) to Hanoi (HAN)?

Yes. VietJet Air, Vietnam Airlines fly this route. Flight time is about 4h 18m.

What is the fastest connection from Osaka (KIX) to Hanoi (HAN)?

via Fukuoka ≈ 4h 48m, via Hangzhou ≈ 4h 48m, via Shanghai ≈ 4h 49m (estimated flying time, excluding layovers).

from 19,000 ANA miles, from 23,000 JAL miles (economy, one way, based on the published award charts).

Kansai International Airport (KIX) to Noi Bai International Airport (HAN)・3,229 km

Nonstop flights available (2 airlines). Flight time about 4h 18m. Nonstop return flights also operate.

With milesANA 19,000 miles+ (via HGH)JAL 23,000 miles+ (via PVG)Economy, one way, estimate. Tap a connection for miles by cabin.

27 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.