A proud Floridian, Horschel enjoyed a stellar collegiate career at the University of Florida. He was a four-time All-American and SEC Player of the Year in 2007 and 2009.

Represented the United States at the Palmer Cup in 2007 and 2008, and helped the US to victory at the 2007 Walker Cup at Royal County Down, winning three points from four matches.

Turned professional in 2009 but had to wait four years for his breakthrough PGA TOUR win, doing so at the Zurich Classic of New Orleans on his 61st start.

Won the PGA TOUR’s FedExCup in 2014 after winning back-to-back play-off events at the BMW Championship and TOUR Championship.

Defeated Jason Day in a play-off to win his fourth PGA TOUR title at the 2017 AT&T Byron Nelson and won the Zurich Classic of New Orleans for a second time in 2018, this time alongside Scott Piercy after it had changed to a team event.

Made his regular DP World Tour debut at the 2019 BMW PGA Championship and was effusive in his praise of the tournament, saying: "The way the Tour puts on a great event, the fans, everything that encompasses this event can rival the best of the best on the PGA Tour in my opinion."

Defeated Scottie Scheffler in the final of the 2021 WGC-Dell Technologies Match Play and later that year became just the second American alongside Arnold Palmer to win the BMW PGA Championship.

Won the Memorial Tournament in 2022 and was selected to represent the US at the Presidents Cup a few months later.

His eighth PGA TOUR victory came at the 2024 Corales Puntacana Championship and he then became the first American golfer to win the BMW PGA Championship twice after defeating Rory McIlroy and Thriston Lawrence in a play-off at Wentworth. Lawrence was eliminated on the first extra hole and Horschel eagled the second sudden-death hole to beat the four-time Major Champion to the title.