Ontario Lottery and Gaming says president and CEO Rod Phillips has resigned to take a job in the private sector.
Phillips had been in the role since 2011, and says his position will be announced by the new organization in February.
OLG chair Philip Olsson says Phillips led the corporation to its highest net profit since 2005, and oversaw the design and launch of the modernization of Ontario's lottery and gaming industry.
The board named OLG executive vice-president Tom Marinelli to serve as acting president and CEO while it searches for a replacement to Phillips.
OLG is responsible for lottery games and gaming facilities in Ontario and has provided nearly $38 billion to the province since 1975.