The 22-year-old Texan had gone 10 straight rounds in major championships without breaking par. That run ended Sunday when he shot a 3-under 68 in the final round at Royal Troon.
Spieth made an eagle at the par-5 fourth hole and added three more birdies on the inward nine to become the first player all day to break par on another windy day along the Irish Sea. It was his best round in a major since a 66 in the opening round of this year's Masters.
"Gained some momentum today," Spieth said. "Saw a couple putts go in from outside 6 feet. Made probably three or four of them today from that range, from anything outside of short range. So my ball striking's there. Really struck the ball good. Held it up nicely, and controlled the spin nicely and played to the right spot. So I played an extremely solid round. Out there wasn't a whole lot better, I don't think.''
Spieth hopes to build on that momentum at the PGA Championship in two weeks. He dropped out of the Rio Olympics, citing health concerns.
"It will be odd when we're there to have played now two majors in three weeks," Spieth said. "I'm sure that will be a different feeling. But, again, I think it's a good feeling if you can ride any kind of momentum from this week, and I think that we can, off of the way that we played the last two days, minus one or two swings yesterday. We were probably 6-under on the weekend. I'm going to spin it however I can to be in my favor and we'll take some confidence."
The Associated Press contributed to this report.