Arizona designated Roberts for assignment earlier Tuesday, ending the Diamondbacks portion of the career of a popular player known to fans as "Tat Man" for his multitude of tattoos.
The team activated shortstop John McDonald from the disabled list on Tuesday to take Roberts' spot on the roster. McDonald had been sidelined since early June with a back injury.
Roberts was the team's regular third baseman in its surprising run to the NL West title a year ago, batting .249 with 19 home runs and 65 RBIs. But his playing time diminished this season and the team recently called up third baseman Ryan Wheeler from Triple-A Reno.
Roberts is hitting .250 with six home runs and 34 RBIs.
In the clubhouse after the move was announced, Roberts thanked the Diamondbacks and the fans.
"That's going to be the No. 1 thing that's going to be tough for me," Roberts said. "I'll definitely miss my teammates. I'll definitely miss the fans that supported me when things were good and when things were bad. That's going to be the thing that hits home the most. Four years here, building friendships knowing everybody from (team president) Derrick Hall down to the bat boys."
Roberts said his time with the Diamondbacks molded him into a major league player.
"It gave me the chance to be the player that I am right now," he said.
Manager Kirk Gibson remembered when Roberts, frustrated by being sent to the minors for the umpteenth time, talked about quitting the game. Gibson said he talked him out of it.
"He's always played hard, to the last game he's played for us," Gibson said. "I have the utmost respect for him and the way he plays. I just would hope that I was just a part of what helped him shape the way he plays. Maybe when he has a great accomplishment someday that I can smile and know that I had an influence in a positive direction."
Information from The Associated Press was used in this report.