Chignecto Bay is an inlet of the Bay of Fundy located between the Canadian provinces of New Brunswick and Nova Scotia and separated from the waters of the Northumberland Strait by the Isthmus of Chignecto. Chignecto Bay forms the northeastern part of the Bay of Fundy which splits at Cape Chignecto and is delineated on the New Brunswick side by Martin Head.

Chignecto Bay also subdivides into basins: The Cumberland Basin forms the northeast arm of Chignecto Bay (and the Bay of Fundy) between the two provinces, terminating at the Tantramar Marshes. Shepody Bay forms the northwest arm of Chignecto Bay and is wholly within New Brunswick. Its northern limit is formed at the estuaries of the Petitcodiac and Memramcook Rivers.