The Diamondbacks officially announced the deal Tuesday. It includes a mutual option.
Kubel, 29, hit at least 20 home runs in three straight seasons from 2008-10 but was limited to 99 games this past year, spending more than a month on the disabled list with a sprained left foot.
He batted .273 with a .332 on-base percentage, 12 homers and 58 RBI, and his .324 average with runners in scoring position ranked 12th in the American League. He led the AL with a .351 average through May 8.
"Jason is a proven, left-handed hitter and corner bat who makes our offense stronger and gives us depth in the outfield," said Arizona general manager Kevin Towers. "His experience will be a welcome addition to our team and in our clubhouse."
Kubel had a .271 average, 104 homers and 429 RBI in 753 games for the Twins.