Spieth, of the United States of America, carded a one-under 69 to win his second major of 2015 by one shot on five under after Dustin Johnson three-putted the last from 12 feet.
At 21, Spieth is one of the youngest players on the Masters circuit, and the single youngest US Open winner since 1923, when golfer Bobby Jones took the title.
His competitor Dustin Johnson was disappointed with his results, saying in a post-match interview that it had been an 'off day', and that although he had 'played good shots, they just weren't going in.' Spieth expressed sympathy for his competitor, saying he “really felt for Dustin.”
The American started the final round at the US Open in the lead, which he shared with Dustin Johnson, South African golfer Branden Grace and Australian player Jason Day.
Spieth and Grace, who was his playing partner, were both five under, but Grace faltered, hitting his tee shot into a tree.
Day looked uncomfortable all day, after having suffered from an attack of vertigo two days prior. Northern Ireland’s Rory McIlroy began the day in strong fashion as he holed six birdies in his opening 13 holes.
McIlroy was pleased with his own performance, saying after the tournament concluded "I'm not sure if I've ever hit the ball that well in a major championship."
Spieth has been quoted as saying he looks to take home the Claret Jug, the trophy at the British Open at St. Andrews where he will next compete.