General manager Bobby Evans says the 30-year-old Romero will begin at extended spring training in Scottsdale, Arizona. Romero last pitched for the Blue Jays in 2013, when he made four appearances with two starts.
An All-Star four years ago, the pitcher was released by Toronto last month. He underwent season-ending left knee surgery last June because of inflammation in his quadriceps tendon.
If Romero is added to the big league roster, the Blue Jays will be responsible for all but the prorated portion of the league minimum on his $7.5 million contract for this year.
He is 51-45 with a 4.16 ERA in parts of five major league seasons.