Reed -- a second-round pick in the 2016 NFL Draft -- spent the last five seasons with the Seahawks.
The 6-foot-3, 306-pound defensive tackle had 38 total tackles, 14 quarterback hits, 6.5 sacks, a pass defensed and a forced fumble in 16 starts last season.
Reed had a career-high 10.5 sacks in 16 starts in 2018. The Seahawks released Reed on Thursday. He will reunite with former Seahawks teammate Frank Clark on the Chiefs defensive line.