Suzuki, 28, considered a defensive specialist, is hitting .218 with one homer and 18 RBI. Over the past three seasons, however, he has averaged .252 with 14 home runs.
The catcher, who is under contract through 2013, passed through waivers and is likely to become the National League East-leading Nationals' No. 1 backstop, General Manager Mike Rizzo told The Washington Post.
"He's not a rental," Rizzo said. "He's going to be here for more than this season. He's a guy that can really take that rotation together and get it going even better than it already is."
Freitas, 23, was hitting .271 at Class A Potomac.