Hendriks was traded to the A's in exchange for Jesse Chavez on Friday, FOX Sports' Ken Rosenthal reports.
He was excellent last year out of the Jays' bullpen, posting a 2.92 ERA with 71 strikeouts in 64.2 innings. That said, Hendriks doesn't figure to get many save opportunities with Sean Doolittle holding down the closer role for the A's.