He began playing the sport when he was four years old and in high school was a member of the Michigan Wolves, an elite level club team.

While living in Grand Blanc, Michigan, Fisher began running in the spring of his seventh grade year, after joining his middle school cross country team.

When he became a freshman in high school, Fisher joined both the soccer and cross country teams, where he made varsity for both.

In the fall of his junior year (2013), he had personal bests of 15:02 at the Foot Locker Midwest Regional to win the event.

[7] This victory made Fisher one of only 5 boys to ever win two Foot Locker national titles (the others included Abdirizak Mohamud, Lukas Verzbicas, Edward Cheserek, and Dathan Ritzenhein).

[11] In Spring of 2015, Grant Fisher became the 7th high school athlete to break 4 minutes in the mile, tying Matthew Maton's time of 3:59.38.

After graduating from the university, the 22-year-old announced his decision to turn professional in June 2019 to compete for the Nike-sponsored Bowerman Track Club.

[22] On March 6, Fisher set another personal best in the 5000 m with a time of 13:02.53 at the Sound Running Invite, also achieving the Olympic standard.

His record-breaking year began at Boston University on February 12, where he set a North American record in the indoor 5000 m with a time of 12:53.73.

On July 17 in Eugene, Fisher placed fourth in the 10000 m final, tying Galen Rupp for the best finish ever in the event at a world championship by an American.

After the World Championships, Fisher participated in three Diamond League events, where he notched several top-three finishes and set two more North American records.

[43] He later announced in early 2024 that he had relocated to Park City, Utah, and was being trained by his high school coach, Mike Scannell.

This was his second national title and his first at 10,000 m.[46] Fisher doubled back to win the 5000 m at the trials with a 13:08.85 just ahead of Abdihamid Nur running 13:09.01.

Additionally, on August 10, 5000 metres final, Fisher secured a second bronze medal with a strong finish, going from ninth to third on the last lap meaning that he placing immediately behind Ronald Kwemoi of Kenya, with a time of 13:15:13.

In October 2024, it was announced that he had signed up for the inaugural season of the Michael Johnson founded Grand Slam Track.

[49]Fisher opened his season on February 2 at the New Balance Indoor Grand Prix, setting a new personal best of 3:33.99 for the 1500 meters in finishing second to Josh Hoey.

[50] On February 8 at the Millrose Games, in the 3000 meters, Fisher outkicked reigning Olympic 1500m gold medalist Cole Hocker over the final straightaway to run 7:22.91, a new world record indoors.

[51] Six days later, competing in the 5000 meters at the BU Valentine Invitational on February 14, Fisher ran 12:44.09, breaking the 20-year-old short track world record of Kenenisa Bekele.