He was born in Strathspey, Moray, Scotland in 1834 to Peter Simpson and Jane Christie Parmouth.

His father was a general store owner, and Simpson was trained in the drapery trade in Elgin, Moray before immigrating to Newmarket, Province of Canada, at the age of 21 where he worked at his uncle's dry goods store.

For decades, Simpson's store was in a rivalry with fellow retailer Timothy Eaton on Yonge Street.

His first store at Main and Timothy Streets in Newmarket is occupied by small retail buildings.

As for the Toronto location at 184 Yonge Street, it was later rebuilt by Robert Jameison and later became the F. W. Woolworth Building.