He played college football for the Michigan Wolverines, winning the Sammy Baugh Trophy, and was selected by the San Francisco 49ers in the eighth round of the 1993 NFL draft.

On the Chiefs, Grbac would help lead the team to two playoff berths and one division title, along with earning Pro Bowl honors in 2000.

[4] Grbac also established the Big Ten Conference career passing efficiency record that would stand for six seasons until it was surpassed by Joe Germaine.

[5] Grbac was a two-time National Collegiate Athletic Association (NCAA) passing efficiency champion during his last two seasons.

Grbac was selected in the eighth round (219th overall) of the 1993 NFL draft by the San Francisco 49ers, where he served as Steve Young's backup from 1994 to 1996.

In Week 11, he led the 49ers to an upset victory over the eventual Super Bowl champion Dallas Cowboys, 38–20, throwing for two touchdowns and running for a third.

Eventually, Grbac was selected to remain the Chiefs starting quarterback; Gannon was released and signed with the Raiders in 1999.

Despite some success, Grbac became unpopular among Chiefs fans because the team's decision to start him over Gannon, who would be named MVP with the Raiders in 2002 and led them to Super Bowl XXXVII.

[25][26] At the end of the season, the Ravens released Grbac in a salary cap move after he refused to renegotiate his contract.

Baltimore's free agent signing of Grbac is considered among the league's worst due to his inefficient performance and lasting only one season with the team.

Sportswriter Jeff Pearlman said this was a mistake by a photographer who, under instructions to profile "the Chiefs quarterback", accidentally took pictures of Grbac instead of the intended Rich Gannon.

[31] Grbac lives in Chagrin Falls and was an assistant quarterbacks coach for St. Ignatius High School in Cleveland, Ohio.

On April 10, 2019, Grbac was named the athletic director and head football coach at his alma mater Villa Angela-St. Joseph High School.

He lives in Chagrin Falls, just outside Cleveland, with his wife Lori (née Immarino) and his three children: Ella, Jack, and Calvin.