After starting the season again in Tacoma, Kelly was called up to the parent Twins and made his major league debut on May 11, 1975. Kelly would play in 49 games with the Twins over the 1975 season, getting into 43 games at first base and two in the outfield. In 147 plate appearances, he collected 15 bases on balls and 23 hits, with five doubles and one home run (a solo blast off Vern Ruhle at Tiger Stadium on 26 May), hitting a poor .181 with 11 runs batted in. Prior to the start of the season, Kelly was purchased by the Baltimore Orioles and assigned to the Triple-A Rochester Red Wings; he would not return to the major leagues as an active player. In 1977, he returned to the Twins organization and Tacoma – spending part of the year as a player-manager. In 1978, Kelly appeared in 119 games for the Twins new Triple-A affiliate, the Toledo Mud Hens. It was his last year as a full-time player.