The author, whose books "A Song of Ice and Fire" have been adapted into the fantasy drama television series for HBO, threw a fundraiser baseball game between Starks-versus- Lannisters, reported Entertainment Weekly.
Martin took to Twitter and shared a photo of himself sitting on an Iron Throne made of baseball bats instead of swords.
"Had a great time at the Direwolves game tonight, check out their cool throne made of baseball bats!"
Fans attended the game in full "Game of Thrones" wardrobe, including some very committed Jon Snows, who came in fur cloaks despite the heat.
The fundraiser benefited the Wild Spirit Wolf Sanctuary in New Mexico, a non-profit that rescues abused and abandoned wolves.