In exchange for the Jamaican defender, the Wizards sent Philadelphia two second round MLS SuperDraft selections, one in 2011 and one in 2012, as well as allocation money.
Thomas has played 151 games for five MLS teams over eight seasons, scoring three goals with one assist. Thomas, 29, played for the Wizards from 2004-2006. He will arrive in Kansas City Wednesday night and will be available for training Thursday.
"We really like Shavar's MLS experience and the strength he brings to our back line," Wizards Manager Peter Vermes said. "We are always looking to improve our roster, and he adds quality depth to the center of our defense."
"I had three wonderful years in Kansas City, and I played some of the best soccer of my career there," Thomas said. "I'm at a place in my career where I can really step up and help the team, and I'm ready to do that. I've played with Jimmy (Conrad), Davy (Arnaud), Jack (Jewsbury) and Josh (Wolff) and have won trophies with those guys, so I am really excited about coming back."