The river's name is an anglicised form of the earlier French settler name "la rivière aux Raisins", which referred to the wild grapes (raisins in French) that can still be found growing along the shores of the river.

[1] The river begins in a field about 2 kilometres (1.2 mi) west of the community of Newington.

It travels south to the community of Bunker Hill, then turns east, and takes in the left tributaries Palen Creek, Shaver Drain and Wereley Creek near the community of North Lunenburg.

The river continues east, takes in the right tributary Glen Drain, passes under Ontario Highway 401, and reaches Lake Saint Francis.

In spring, the "Raisin River Canoe Race" runs from Saint Andrews to Williamstown.