He went 1-for-5 with a strikeout in the Yankees' 9-3 win.
"Most of the muscle soreness and tightness is out of there, so that's a great step," Teixeira said after the game. "It was great to play today."
Teixeira approached manager Joe Girardi early Sunday morning and pronounced himself healthy enough to play first base in the series finale against the Toronto Blue Jays.
"I didn't even ask him," Girardi said before the game.
Teixeira suffered the injury to his right knee on Thursday night, when he was hit by an 83-mph cutter from Boston Red Sox right-hander Alfredo Aceves. He sat out the first two games of the Toronto series and said on Saturday that he was concerned about his right hamstring tendon as well as the knee.
But after receiving extensive treatment from team trainers on Friday and Saturday, Teixeira pronounced himself ready to play on Sunday morning.
The 31-year-old Teixeira entered Sunday hitting just .248 in 134 games this season but has belted 35 home runs and also has 100 RBIs.
In addition to his production at the plate, the Yankees also missed Teixeira's Gold Glove-caliber fielding at first base over the last two games. He was replaced at first by regular right-fielder Nick Swisher.
"He's got so much experience over there," said Girardi, adding that Swisher did a fine job at first in Teixeira's absence.
Ian Begley is a frequent contributor to ESPNNewYork.com. Information from ESPNNewYork.com's Matt Ehalt was used in this report.