The throughbred's accomplishment marks the second horse to win the elusive three races in three years, as American Pharoah also took home the tile in 2015.
The muscular horse is 1,268 pounds, more than 100 pounds more than American Pharoah, the Baffert-trained horse that won the Triple Crown in 2015, and stands at 16.3 hands high, slightly taller than American Pharoah.
Baffert will saddle a second horse: 30-1 shot Restoring Hope.
He knew in February that the 3-year-old chestnut colt, who had yet to run a race, was something special.
The horse, part owned and named after star Patriots tight end Rob Gronkowski, was in last place early in the race, but stormed back towards the front at the end, finishing just under two lengths behind Justify. The biggest threat to Justify's chances in the 10-horse field is Hofburg, who has 9/2 odds. "I'd like to see the horse win it for himself".More news: Robert Whittaker vs. Yoel Romero II is going ahead after all
The 2018 Belmont Stakes Saturday will determine whether Justify clinches the Triple Crown or comes up a race victory short.
John Velazquez was already asking Vino Rosso for more run nearing the quarter pole, while Smith had yet to even loosen his reins on Justify. He won the Kentucky Derby and Preakness on sloppy tracks after heavy rain fell.
Justify battled nine rivals, the largest number that a potential Triple Crown victor has ever faced.
This was only his sixth race, and some bettors anxious that he packed too many races in the past 110 days. In defeating nine foes in the Belmont Stakes, he turned back the largest field to challenge a potential Triple Crown victor, yet another element that allows him to stand alone.
Justify became the 13 horse to sweep the Triple Crown, having already won the Kentucky Derby and Preakness.
Post time for the Belmont Stakes is scheduled for 5:46 CDT Saturday at Belmont Park in Elmont, New York, and it will be about two-and-a-half minutes before the American classic has its 150 victor. "But the thing that has me a bit anxious is the last horse to win the Belmont drawing the rail was Empire Maker in 2003 - in a six-horse field".
After his first few months in training, Justify had a little time off before he was sent to trainer Rodolphe Brisset's barn at Keeneland, where he would have his first several breezes on the racetrack.