The Blue Jays signed Walker to a one-year, $760,000 contract, Ben Nicholson-Smith of Sportsnet.ca reports.
The Pirates signed Walker to a minor-league contract Saturday and placed him on the 7-day injured list, Alex Stumpf of MLB.com reports.
The Pirates released Walker on Saturday.
Walker will report to Triple-A Indianapolis Tuesday, Andrew Destin of the Pittsburgh Post-Gazette reports.
The Pirates acquired Walker from the Mets on Tuesday, Andrew Destin of the Pittsburgh Post-Gazette reports.
Walker was optioned to Triple-A Syracuse on Sunday.
The Mets recalled Walker from Triple-A Syracuse on Wednesday, Tim Healey of Newsday reports.
The Mets optioned Walker to Triple-A Syracuse on Wednesday, Anthony DiComo of MLB.com reports.
The Mets recalled Walker from Triple-A Syracuse on Thursday.
The Mets optioned Walker to Triple-A Syracuse on Sunday.