Are there nonstop flights from Athens (ATH) to Kithira Island (KIT)?

Yes. Sky Express (Greece), Olympic Air fly this route. Flight time is about 44m.

Athens → Kithira Island

Athens Eleftherios Venizelos International Airport (ATH) to Kithira Airport (KIT)・202 km

Nonstop flights available (2 airlines). Flight time about 44m. Nonstop return flights also operate.

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