The RMG was founded in 1967 after Oshawa designer William Caldwell organized an exhibition of work by local artists at a commercial space on Simcoe Street. Seeing the need for a more permanent home for the arts, Ewart McLaughlin and his wife Margaret (painter Alexandra Luke) offered major financial support and works from their own private collection toward the establishment of an expanded public art gallery for the City of Oshawa.
The gallery was incorporated with name of Robert, founder of The McLaughlin Carriage Company, grandfather of Ewart, and father of Col. R.S.(Sam) McLaughlin (General Motors of Canada). Isabel McLaughlin, an important modernist painter and cousin of Ewart, also became a life long patron of the gallery. A founding member of the Canadian Group of Painters, she provided ongoing generous financial support as well as significant gifts of over 100 works of important Canadian and international works.
The RMG is independently incorporated, goverened by an elected Board of Trustees, operating with professional staff and volunteers. Support is generously provided by The City of Oshawa, The Ontario Arts Council, The Canada Council for the Arts, Department of Canadian Heritage - Museum Assistance Program and the RMG Volunteer Committee.