Francisco, 31, was hitting .244 with two home runs and seven RBIs in 144 plate appearances with the Blue Jays and Astros this season.
He has a .258 career average with 47 home runs and 181 RBIs in 518 Major Leagues with the Phillies, Indians, Astros and Blue Jays.
"Nice outfielder, pretty good hitter also," Rays manager Joe Maddon said of Francisco. "If you put him in the right spots, he can be very productive. Really balances us out even better where if we see a left-hander, now we can have three righties in the outfield now, so that's kind of a nice thing."
The Rays will need to make a corresponding move to their 40-man roster to make room for Francisco, who is expected to join the team on Saturday.