The 37-year-old right-hander was 51-68 for Boston (1999-01), Montreal (2001-04), Washington (2005), Milwaukee (2005-06), Toronto (2007) and Cleveland (2009). He has played in Japan for Yokohama (1995-98 and 2010-11) and Toyama (2013).
Blue Jays general manager Alex Anthopoulos said Thursday that Ohka likely would start the season at Double-A New Hampshire.
"We want to see how he does," Anthopoulos said. "There's no downside to us to signing a minor league contract. We know him before: a good athlete, strike-thrower, determined, and we'd like to see if we can get him to bounce back."