NokScoot airline will launch a four-flights-a-week service between Bangkok and Osaka's Kansai airport on Oct 28, using a Boeing 777-200 with 415 passenger seats.
It will be the second route to Japan for the medium-haul, low-cost carrier. The Bangkok-Tokyo service launched in June.
"We are excited about flying to Japan's second largest metropolitan area, which is rich in history and famed for its food and nightlife scenes," NokScoot chief executive Yodchai Sudhidhanakul said on Friday.
Kansai airport, besides serving Osaka, was also the gateway to world-renowned tourist sites in western Japan, including Kyoto and Kobe, he said. Osaka, with 9.4 million arrivals in 2016, nearly a third up from the previous year's level, was also fast becoming a destination in its own right.
Although there would be four airlines operating non-stop flights between Bangkok and Osaka, NokScoot would attract customers with its great value-for-money offering, he said. The airline set its promotional ticket price for one-way trips at 3,599 baht. The promotion was available until Sept 19 for trips made between Oct 28 and March 30 next year.
For Thais, Osaka was the second most visited Japanese city after Tokyo, with about 850,000 travelling between Bangkok and Osaka annually, Mr Yodchai said.