Broomspun got a late start to his three-year-old season, making his sophomore debut in an allowance race at a mile and one eighth at New York's Aqueduct Racetrack. In that race, he ran second. Later that year, after the Derby runner did not return two weeks later in Baltimore, trainer James Rowe entered Broomspun in the second jewel of Triple Crown, the Preakness Stakes. In that race, four multiple stakes winners were assigned the high weight of 126 pounds. Broomspun, because of his lack of success, was given a weight allowance of 12 pounds and went to post carrying 114 pounds including his jockey, Frank Coltiletti. In 1921, the Preakness was the richest race held in North America. While $38,450 went to the winner of the Kentucky Derby, the Preakness victor received $43,000.[2] A record 30,000 race fans were on hand, the most in the 48-year history of the race.
At the start of the race, several of the 14 starters were fractious or unruly as it took the starter eleven minutes to get the field settled. Broomspun broke from post position 7 in a forward position and stalked the leaders from fourth passing the stands for the first time at Pimlico Race Course. He sat just off leader Leonard II's flank going down the backstretch in 47.4 for the first half mile. On the final turn, Broomspun worked his way around on the outside and burst down the lane to take the lead by just over a length. In the final strides, he was ridden out hard by jockey Frank Coltiletti to hold for the win by three quarters of a length over a hard-charging filly named Polly Ann.
The headline in The Baltimore Sun the next day read, "From obscurity to fame, Broomspun jumped in less than two minutes in The Preakness Stakes. The 3-year-old son of Broomstick and Spun Giass, who is the property of Harry Payne Whitney, the New York City sportsman, won the Classic Preakness from a field of 14 strong competitors, the best three-year-olds in the country." Besides beating Polly Ann, Broomspun defeated Jeg, who held on for third, and Leonardo II and Tryster, who dead-heated for fourth. That win was owner Harry Payne Whitney's second of four in the Preakness Stakes.
While competing in the June 18, 1921 Carlton Stakes at New York's Aqueduct Racetrack, jockey Clarence Kummer felt Broomspun's leg give on his first stride at the start of the race and pulled him up after four furlongs. Broomspun was euthanized when it was determined he had broken his right foreleg at the shoulder.[3][4]