Are there nonstop flights from Seoul (GMP) to Kaohsiung (KHH)?

Yes. Trinity Airways, Jeju Air, Tigerair Taiwan fly this route. Flight time is about 2h 35m.

What is the fastest connection from Seoul (GMP) to Kaohsiung (KHH)?

via Jeju City ≈ 3h 8m, via Busan ≈ 3h 18m, via Osaka ≈ 4h 17m (estimated flying time, excluding layovers).

from 11,000 ANA miles (economy, one way, based on the published award charts).

Seoul Gimpo International Airport (GMP) to Kaohsiung International Airport (KHH)・1,776 km

Nonstop flights available (3 airlines). Flight time about 2h 35m. Nonstop return flights also operate.

With milesANA 11,000 miles+ (via KIX)Economy, one way, estimate. Tap a connection for miles by cabin.

4 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.