"He's going to join us tomorrow," Francona said on Wednesday.
Perez completed a Minor League rehab assignment with Class A (short season) Mahoning Valley on Tuesday, logging one strikeout in one inning. That represented the final step in the rehab process for Perez, who was shelved with a strained right rotator cuff after an outing against the Red Sox on May 26 in Boston.
Francona said Perez's last rehab game went well.
"He felt good. The reports were good. He did a good job," Francona said. "And I know it's kind of popular thinking that C.P. sort of has his own opinions and everything, but he couldn't have been better with us in communicating and doing what we asked and being honest."
Perez has a 4.32 ERA in 17 appearances, during which he has six saves, 18 strikeouts and 10 walks in 16 2/3 innings. The right-hander's line is marred by his last three outings, which included a 23.63 ERA (seven runs, five walks, five hits and three strikeouts in 2 2/3 innings). Prior to that stretch, Perez posted a 0.64 ERA in his first 14 games.
When Perez officially rejoins the bullpen, interim closer Vinnie Pestano will return to his customary setup role. That will also allow sidearmer Joe Smith to shift back to his seventh-inning duties, and push the rest of the bullpen back into middle-relief innings.
"What'll be nice is when we get everybody back," Francona said, "and everybody is on all cylinders."
Jordan Bastian is a reporter for MLB.com. Read his blog, Major League Bastian, and follow him on Twitter @MLBastian. This story was not subject to the approval of Major League Baseball or its clubs.