Whitby—Ajax

| fed-status = defunct | fed-district-number = | fed-created = 1996 | fed-abolished = 2003 | fed-election-first = 1997 | fed-election-last = 2000 | fed-rep = | fed-rep-party = | fed-rep-color = | demo-pop-ref = | demo-area-ref = | demo-electors-ref = | demo-census-date = 2001 | demo-pop = 128164 | demo-electors = 83443 | demo-electors-date = 2002 | demo-area = 188 | demo-cd = | demo-csd = Whitby, Ajax

Whitby—Ajax was a federal and provincial electoral district in Ontario, Canada. It was represented in the House of Commons of Canada from 1997 to 2003, and in the Legislative Assembly of Ontario from 1999 to 2007. It was located to the east of Toronto, consisting of the Town of Whitby and the part of the Town of Ajax lying to the south of Kingston Road.

The federal riding was created in 1996, from parts of Durham and Ontario ridings, while the provincial riding was created in 1999 from Durham Centre, Durham East and Durham West.

The federal electoral district was abolished in 2003 when it was redistributed between Ajax—Pickering and Whitby—Oshawa ridings. The provincial electoral district was abolished in 2007, when it was also redistributed into Ajax—Pickering and Whitby—Oshawa.