Kennedy signed a minor-league contract with the Red Sox on May 25.
Boston assigned him to Double-A Portland, with whom he tossed three scoreless innings in his first appearance Thursday. Before signing with Boston, Kennedy had been pitching in the independent Atlantic League of Professional Baseball with the Long Island Ducks. The 27-year-old righty previously made his MLB debut with the Padres in 2018, but he hasn't resurfaced in the majors since making six starts for San Diego that season.