It was the third straight win for Pacquiao and 62nd victory of his career – and included a first-round knockdown of Thurman.
Thurman, 30, a native of Florida, had come into the match undefeated.
"It was fun," Pacquiao told the Associated Press afterward. "My opponent is a good fighter and boxer. He was strong. ... I think he did his best, and I did my best. I think we made the fans happy tonight because it was a good fight."
"I think we made the fans happy tonight because it was a good fight."
Two of the evening's judges scored the bout 115-112 in favor of Pacquiao, while Glenn Feldman scored it 114-113 for Thurman. The Associated Press also scored it 115-112 for Pacquiao.
Both fighters came out punching in the first round -- then Pacquiao combined a left to the body and a right hook to send Thurman to the canvas 25 seconds before the bell.
But Thurman recovered and the fight went the distance before a sellout crowd.
"I knew it was close," Thurman said about the scoring, according to the Associated Press. "He had the momentum because he got the knockdown in Round 1. ... I wish I had a little bit more output to go toe to toe. My conditioning, my output was just behind Manny Pacquiao's tonight. Tonight was a blessing and a lesson."
After the decision, Thurman called for a rematch, and the crowd cheered in approval.
The Associated Press contributed to this story.