It was named in honour of Sir John Wentworth, the last royal governor of colonial New Hampshire, lieutenant-governor of Nova Scotia (1792 to 1808) and an intimate friend of William Jarvis, the first provincial secretary of Upper Canada.
Between 1850 and 1854, Wentworth County and Halton County were briefly joined for government purposes as the United Counties of Wentworth and Halton although for administrative purposes, they remained distinct.
In 1973, Wentworth County was replaced by the Regional Municipality of Hamilton–Wentworth.
Each township that was ever part of the county is listed alphabetically below along with its years of existence, and its previous and subsequent configurations.
Source: Province of Ontario -- A History 1615 to 1927 by Jesse Edgar Middleton & Fred Landon, copyright 1927, Dominion Publishing Company, Toronto]