[3] He later attended Cherry Creek High School in Greenwood Village, Colorado, while his father served as head coach of the Denver Broncos.

[9][10] As a graduate assistant, he worked with players like Maurice Jones-Drew, Marcedes Lewis, and Drew Olson,[11] but he still had to take classes and could not spend all his time on football.

[13] As a quality control coach, Shanahan helped break down game film and drew diagrams of plays for the playbook.

[16] In 2007, he had also been offered to become offensive coordinator at the University of Minnesota, where former Broncos assistant Tim Brewster just became head coach.

[17] Shanahan was immediately considered the frontrunner for the vacant offensive coordinator position after Mike Sherman had left the Texans to take over as head coach at Texas A&M University.

[18] On January 11, 2008, Shanahan was officially promoted, becoming the youngest coordinator in the NFL, being more than three years younger than Josh McDaniels of the New England Patriots.

[23] Prior to his hiring by the Browns, Shanahan interviewed for the vacant offensive coordinator jobs held by the Miami Dolphins[24] and Baltimore Ravens.

[25] On January 8, 2015, Shanahan resigned from his offensive coordinator position due to friction with head coach Mike Pettine and possibly how the front office was run.

[32][33] On February 6, 2017, one day after the Super Bowl, Shanahan was officially hired as the next head coach of the San Francisco 49ers, signing a six-year deal.

[39] Three weeks later, the 49ers pulled out a narrow 15–14 road victory over the Chicago Bears, which marked the first start for quarterback Jimmy Garoppolo as a 49er.

[67][68] During the NFC Championship Game against the Philadelphia Eagles, the 49ers were forced to substitute Josh Johnson in for an injured Purdy.

[69] For the season, Shanahan came in second place in voting for the AP Coach of the year award, this time behind Brian Daboll of the Giants.

[71] In 2023, he led the 49ers to a 12–5 record, winning the NFC West for the second straight season and being named a finalist for the AP Coach of the Year award.

[70][72] He led the team to victories over the Green Bay Packers in the Divisional Round and the Detroit Lions in the NFC Championship, where they stormed back from a 24–7 halftime deficit against Detroit, en route to Super Bowl LVIII, where San Francisco would face the Kansas City Chiefs in a rematch of Super Bowl LIV.

[73][74] Like the initial matchup between the two teams four years earlier, the 49ers opened up a 10-point lead before Kansas City rallied and eventually emerged victorious yet again, this time by a score of 25–22.

He received backlash for electing to receive possession first in overtime after winning the coin toss, rather than allow the Patrick Mahomes and Chiefs offense to see the field first, which would have allowed the 49ers to gameplan based on the result of Kansas City's drive due to both offenses getting an opportunity in the extra period, regardless of whether a touchdown was scored or not, after new postseason overtime rules were implemented following the 2021–22 NFL playoffs.