With the season-ending injury to Jose Contreras and the demotion of Boone Logan, the team's hand was all but forced to make a move.
Ramirez struggled after being traded from the Braves to the Mariners, but was given a chance with the Royals, who signed him to a Minor League contract on May 21.
He seemed to find his groove out of the bullpen after the change of scenery, posting a 2.59 ERA in 24 1/3 innings. He struck out 11 against just one walk during that span.
"I think I'm just keeping things simple," said Ramirez, who strolled into the White Sox clubhouse with a Royals duffel bag. "I'm simpler out there. Last year, I pressed too much. I tried too hard. And it came back and got me.
"I think I've had a good amount of solid outings and keeping the ball down in the zone and getting late movement. I'm a ground-ball pitcher."
The White Sox sorely need somebody to give the bullpen a boost. The relief corps has struggled in the second half, going from the best bullpen in the Majors to the sixth-best with a 3.50 ERA.
White Sox manager Ozzie Guillen said he'd like to see D.J. Carrasco take the spot in the rotation left by Contreras, but Ramirez has started capably in the past.
"He hasn't done that in a little while," Guillen said. "I think the role he had in Kansas City is the perfect role for him. That's the way to keep him fresh and keep him healthy."
"He really pitched good against us," Guillen continued. "If this kid's healthy, he can help us."
Ramirez arrives just two days before the White Sox begin a three-game set against his former team, the Royals. The two teams were involved in a bench-clearing incident during their last series.
"It's going to be a little crazy," Ramirez said. "If anything happens, I might be the peacemaker."
David Just is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.