EW.com said HBO didn't specify the number of episodes the season will have, but said it will likely be comprised of 10 episodes, as did the previous seasons.
Starring Peter Dinklage, Aidan Gillen, Emilia Clarke and Lena Headey, the show kicked off its third season Sunday night.
Michael Lombardo, president, HBO Programming, said in a news release the season premiere drew the series' largest audience to date, averaging 4.4 million viewers in its 9 p.m. EDT time slot -- up from the previous record of 4.2 million who tuned in for last season's finale.
"Game of Thrones" is based on the fantasy book series by George R.R. Martin.