Dellucci will be assigned to Triple-A Las Vegas, where manager Cito Gaston said he will get some at-bats before being considered for the big league club.
"He can swing the bat, and we needed a left-handed hitter to help out [Lyle] Overbay and [Adam] Lind," Gaston said. "We needed more help from the left side."
The Blue Jays started the season with outfielder Travis Snider as another left-handed-hitting option, but he batted only .242 and was optioned to Las Vegas on May 22.
Snider is struggling with back problems, and he isn't expected to play again until July.
Dellucci, 35, was released earlier this month by the Cleveland Indians. He was batting .275 with an RBI in 40 at-bats. He will make the prorated minimum salary.
Todd Wills is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.