Awesome to see 2 great guys working together- my 2 longtime friends John Schneider & top client Ryan Grigson working together with the @Seahawks— Buddy Baker (@ESG_Baker) June 13, 2018
Grigson will be a consultant, a source told ESPN's Brady Henderson.
Grigson was a senior personnel executive with the Cleveland Browns last season but was let go after John Dorsey took over as general manager late in the season, replacing Sashi Brown.
Grigson, 46, was relieved of his GM duties by the Colts in January 2017 with three years remaining on his contract.
He was a first-time GM with the Colts when he replaced Bill Polian in 2012. He selected quarterback Andrew Luck with the No. 1 overall pick in his first draft and also selected tight ends Dwayne Allen and Coby Fleener and Pro Bowl receiver T.Y. Hilton in that draft.
The Colts went 11-5 in each of his first three seasons and advanced to an AFC Championship Game but missed the playoffs with 8-8 records in his final two years at the helm.
His missteps with the Colts included trading a first-round pick in 2013 to the Browns for Trent Richardson only to cut the running back two years later after he failed to make an impact, and failing to address Indianapolis' offensive line needs in a timely fashion.
Grigson didn't make a full commitment to improve the offensive line until the 2016 draft, when the Colts used half of their eight picks on linemen. That commitment came only after Luck missed nine games because of injury in 2015.
ESPN's Mike Wells contributed to this report.