Grimble, 25, originally signed on with the Giants as an undrafted free agent out of USC back in 2014. He lasted just a few months with the Giants before eventually signing on to the 49ers’ practice squad at the start of the season.
Grimble had a brief stint with the Patriots before returning to the 49ers on a future/reserve contract in 2015. The Steelers later added him to their taxi squad and re-signed him to an exclusive rights contract last year.
In 2017, Grimble appeared in 15 games for the Steelers and caught five passes for 32 yards receiving and one touchdown.