Burns has appeared in 72 games with 38 starts since the Steelers selected him in the first round of the 2016 draft. He has four career interceptions with 33 passes defensed. He played just 16 defensive snaps and eight special teams snaps last year.
The Seahawks also signed fourth-round pick Anthony Bradford, a guard out of LSU.
Seattle now has seven of its 10 draft picks under contract.
As a corresponding move to add Burns, the Seahawks waived nose tackle Robert Cooper. He had joined the team as an undrafted free agent earlier this month.
Seahawks sign Artie Burns, fourth-round pick Anthony Bradford originally appeared on Pro Football Talk