Walter, 27, originally signed on with the Chargers as an undrafted free agent out of Cornell back in 2010. He has since played for the Vikings and Seahawks.
Seattle declined to tender Walter a qualifying offer, making an unrestricted free agent.
Last year, Walter appeared in 13 games for the Seahawks and caught six passes for 57 yards receiving and no touchdowns. Pro Football Focus has him down for playing 108 total snaps in 2014.