Hawaiian pizza was invented in Canada, specifically at the Satellite Restaurant in Chatham, Ontario, in 1962 by Sam Panopoulos, a Greek immigrant. He created the pizza by adding canned pineapple to traditional pizza with ham, inspired by the sweet and savory combinations in Canadian Chinese cuisine. The name "Hawaiian" comes from the brand of canned pineapple used, not the U.S. state of Hawaii.
While there is an earlier documented instance of a pizza called "Hawaiian" with pineapple in Portland, Oregon in 1957, Panopoulos's creation in Canada is widely recognized as the popular origin of Hawaiian pizza.