The Waterloo electoral district was created in 1966 from parts of Waterloo North and Waterloo South electoral districts. It initially comprised the City of Waterloo, the City of Galt, and the Townships of North Dumfries and Waterloo.
After the amalgamation of the City of Galt with the Towns of Preston and Hespeler into the City of Cambridge in 1973, the name of the electoral district was changed to Waterloo—Cambridge, The boundaries of the district were not changed.
In 1987, the Waterloo electoral district was redefined to comprise the City of Waterloo, the northern part of the City of Kitchener, and the Township of Woolwich. The Townships of Wellesley and Wilmot were redistributed to the Perth—Wellington—Waterloo district.
Following the 2011 Census and a Canadian Parliament decision to increase the number of Federal electoral districts from 308 to 338, Elections Canada conducted a redistribution process that began with the establishment of Electoral Boundaries Commissions for each province in 2012. As a result of the work of the Electoral Boundaries Commission for the Province of Ontario, which was concluded in July 2013, the Kitchener-Waterloo district was abolished, with most of its territory being redistributed to a new Waterloo electoral district.
The new Waterloo electoral district includes all of the City of Waterloo and the portion of the City of Kitchener lying northerly of the Canadian National Railway and northeasterly of Conestoga Parkway.
Any Canadian federal general election taking place after April 2014 will be based on the electoral districts established by the Electoral Boundaries Commissions in 2013, meaning that the Waterloo electoral district will again be represented in the Canadian House of Commons after the 42nd Canadian federal election (expected sometime in 2015).