Seattle hosted Mitchell on a visit earlier this offseason and has a hole at the spot following DL Jarran Reed‘s six-game suspension.
Mitchell, 31, is a former third-round pick of the Texans back in 2010. He spent four years in Houston before signing a four-year, $19 million contract that included $8 million guaranteed with the Dolphins.
The Dolphins released Mitchell in 2017 and he later agreed to a four-year, $16 million contract with the 49ers. He was set to make base salaries of $2.85 million over the final two years of the agreement when the 49ers declined his option this offseason.
In 2018, Mitchell appeared in 14 games for the 49ers and recorded 28 tackles and no sacks.