The accident, blamed on a landing-gear malfunction, occurred late Sunday at Suvarnabhumi Airport.
The plane carried 14 crew members and 288 passengers, CNN reported.
The airline, in a statement Monday, said the Airbus A330-300 on flight TB679 had departed Gangzhou, China, at 9:25 p.m. local time for Bangkok and skidded off the runway upon landing at the Thai capital airport at 11:20 p.m., the Bangkok Nation reported.
"After touchdown at Suvarnabhumi Airport, the landing gear malfunctioned and caused the aircraft to skid off the runway," the airline said. "Sparks were noticed from the vicinity of the right landing gear near the engine; the matter is under investigation."
After the plane came to a halt, passengers were evacuated from emergency exits.
The injured passengers were taken to a hospital.
Airport officials worked Monday to clear the runway and did not rule out delays.
On Aug. 30, a Thai Airways A380 plane with 500 passengers from Bangkok hit severe turbulence during its approach into Hong Kong International Airport, injuring 39 passengers, CNN said.
The Wall Street Journal, quoting analysts, said Thai Airways is considered to be one of Southeast Asia's safest and best-run airlines. The Sunday incident was its worst aircraft accident since March 2001.