The 'I Believe I Can Fly' singer postponed the New York event celebrating the release of his new book Soulcaster "due to a health emergency that has sidelined [him] in Chicago", according to his rep.
TMZ reports that the soul singer is dealing with complications from a surgery he underwent last year to treat an abscess on his vocal cords.
A rep added that Kelly wants to "sincerely apologise for any inconvenience this has caused".
The 45-year-old's health problems also forced him to cancel an appearance on NBC's The Today Show as well as Jimmy Fallon's late night talk show.
Kelly recently faced legal troubles after amassing a $5m debt in back taxes.
Watch the video for R Kelly's 'Happy People' below: