[6] On February 24, 2017, Mitchell signed a four-year, $16 million contract with the San Francisco 49ers.

[7] In his first season in San Francisco, Mitchell started all 16 games, recording 33 combined tackles, one sack, and a career-high four passes defensed.

On January 23, 2019, the 49ers declined the two-year option on Mitchell's contract, making him a free agent in 2019.

[12] Mitchell reached Super Bowl LIV with 49ers, but lost 31–20 to the Kansas City Chiefs.

[13] Mitchell was born and raised in Houston, moving around with his mom, who separated from his dad.