Horcoff played his first college season with Michigan State University, in the Central Collegiate Hockey Association (CCHA), in 1996.

After a respectable first season in which he was considered a contender for the CCHA All-Rookie Team,[1] Horcoff improved his numbers as a sophomore in 1997–98, despite playing in fewer games than the year before.

While at Michigan State, Horcoff studied finance and mathematics, receiving his degree before beginning his professional hockey career.

[4] After leaving university, Horcoff failed to make the 2000–01 Edmonton Oilers out of training camp, and was assigned to their American Hockey League (AHL) affiliate, the Hamilton Bulldogs.

[5] During the NHL lockout, Horcoff sought out a team where he would be able to play more of an offensive role.,[7] and signed a contract with for Mora IK of the Swedish Elitserien.

This season marked a turning point in his career, where he played the role of an offensive leader (finishing fourth in the league in scoring) with a professional team.

In addition to a demanding conditioning regimen, Horcoff went to the Easton Hockey factory in Tijuana, Mexico, and had a stick custom designed for him.

On October 6, 2010, Horcoff was named the 13th captain in Edmonton Oilers' history, succeeding Ethan Moreau, who had departed the team for the Columbus Blue Jackets in the previous off-season.

After completion of the lockout-shortened 2012–13 season, on July 4, 2013, Horcoff was traded by the Oilers to the Dallas Stars in exchange for defenceman Philip Larsen and a seventh-round draft pick in 2016.

Horcoff and former Major League Baseball (MLB) outfielder Jason Bay are friends, having grown up near each other in British Columbia.