Knowles was one of snooker's finest players during the 1980s, reaching No 2 in the rankings and winning several tournaments. He is currently competing on the Challenge Tour.
The 49-year-old is now set for a second spell on the WPBSA board.
Six of the seven members of the existing WPBSA Board were standing for election or re-election at the AGM - Sir Rodney himself, Peter Ebdon, Adrian Metcalfe, Sir Robin Miller, Tony Murphy and David Richards.
Following the players’ vote, Knowles will replace Adrian Metcalfe.
