The four-year contract is worth about $12.5 million, according to ESPN. The deal could max out at $16 million. The guaranteed portion of the agreement is $3.5 million.
Washington was part of a draft-day trade last season from the Jets to Seattle, and finished second to Joshua Cribbs of the Browns in Pro Bowl voting among AFC return specialists.
Washington had 27 rushes for 100 yards. As a returner, he had 57 kickoff returns, a 25.6-yard average per return and scored three touchdowns. As a punt returner, he had 22 chances with an 11.3 average, a career high.