Geroux was born in 1986 Argentan, France. His father Dominique was a jockey and later a trainer in France. At age 13, Geroux was accepted into the French riding academy, Afasec. He later started riding in France and became a leading apprentice. He secured his first win on May 6, 2004 at Longchamp on Chopyluz. Geroux married Kasey Spindler, whose father was a Chicago-based jockey, Louis Spindler. The couple have two children, Olivia and Celine. On May 23, 2018, Geroux became a U.S. citizen, taking the Oath of Allegiance at the naturalization ceremony in Louisville, Kentucky.
Geroux came to the United States for the first time in early 2007, working with trainer Patrick Biancone for a few months before returning briefly to France. In the fall of 2007, Geroux returned to the United States with the intention of joining the Kentucky racing circuit. On the opening day at Keeneland, he suffered a serious fall, suffering a broken wrist and two fractured vertebrae. He recuperated in France for several months then returned to the States with Chicago as his home base. He enjoyed some success over the next years, finishing tenth in the Arlington jockey standings in 2010 and winning the 2011 Hawthorne meet. He earned his first stakes wins on Zoeling in the 2010 Leemat Stakes at Presque Isle Downs. In 2010, Geroux changed agents to Doug Bredar and gradually climbed the jockey ranks in the Chicago area. In 2014, Geroux scored his first Grade I victory in the Breeders' Cup Sprint aboard Chicago-based Work All Week. In 2015, Geroux relocated to Kentucky and was the leading rider at Kentucky Downs, where he won five races on two different days, and also led the Fair Grounds 2015-6 meet. He won the Arlington Million with The Pizza Man and the Breeders' Cup Juvenile Fillies Turf with Catch a Glimpse and the Breeders' Cup Turf Sprint with Mongolian Saturday. Geroux had a career best year in 2016, with earnings of $17,690,013 and 217 wins, including two Grade I wins on I’m a Chatterbox. He picked up the mount on Gun Runner at the start of the year and rode him to a win in the Louisiana Derby and a third-place finish in the Kentucky Derby. After the pair finished second in the Breeders' Cup Dirt Mile, they capped the year with a win in the Clark Handicap. Another highlight was winning four graded races on Arlington Million Day: the Beverly D, Secretariat, American St. Leger and Pucker Up. He earned his 1,000th North American win on December 29 aboard Mr. Misunderstood at the Fair Grounds. In 2017, Geroux was ranked in the top ten of North American jockeys. With Gun Runner, he won the Breeders' Cup Classic and four other stakes race, plus a second-place finish in the Dubai World Cup. "You ride a thousand horses a year, and this one, there's just something special," said Geroux of his connection in Gun Runner. "I'm not a true believer in that, but I do believe now."
