Local 225 was originally chartered in 1947 by the Office and Professional Employees International Union (OPEIU). It's mandate was to organize and represent members for Ottawa based organizations. OPEIU's jurisdiction was considered white collar workers but in time the jurisdiction would be expanded to included those workers who did not easily fall into blue or white collar brackets such as workers for social agencies and union representatives.

Under the original OPEIU regional distribution system, Local 225 was part of the Eastern Canada Council which had all the Maritime, Quebec and some Eastern Ontario based locals. The Eastern Canada Council had Montreal as its base of operations. The regional divisions were eventually restructured that forced Local 225 to move to the Central Ontario Council since the Eastern Canada Council was converted into the Quebec Regional Council.

In 2004, the Canadian locals of OPEIU decided to separate from the International Union and create the Canadian Office and Professional Employees Union (COPE). With the later mergers of the Central Ontario Council and the Mid-Canada Councils, Local 225 is now part of the COPE Ontario Region.