Big Brown, favored to be the 12th Triple Crown champion after winning the Kentucky Derby and the Preakness, was third at the three-quarter pole, behind 38-to-1 Da'Tara and Tale of Ekati, but ended up finishing last. Da'Tara, ridden by Alan Garcia, pulled away down the stretch.
Denis of Cork, who was third in the Kentucky Derby, came in second. Anak Nakal and Ready's Echo finished in a dead heat for third.
Big Brown, ridden by Kent Desormeaux, was trying to become the first thoroughbred to win the Kentucky Derby, Preakness and Belmont in the same year since Affirmed in 1978. He went off at 1-to-4 after being undefeated in five previous career starts.
"I salute Big Brown," Da'Tara trainer Nick Zito said. "He's still a champion. He just wasn't himself today. We took advantage of it."
Big Brown lost contact with the field at the top of stretch, causing Desormeaux to stop riding the colt. The 3-year-old jogged the rest of the way to finish last in the nine-horse field. There had been concern going into the race about a quarter-crack in Big Brown's left front foot. He has been treated by hoof specialist Ian KcKinlay and raced Saturday with an acrylic patch.