Mayer says it isn't clear when the Chicago native might be well enough to resume performing.
The Grammy-winning singer had complained of throat pain and was taken to the hospital on Tuesday. The same day, surgeons drained an abscess on one of his tonsils.
The self-proclaimed Pied Piper of R&B released a critically acclaimed retro-soul album last year, titled "Love Letter." He recently completed the U.S. leg of a worldwide tour.
Kelly won a Grammy in 1997 for his gospel-tinged "I Believe I Can Fly."