Greenock Township was settled more slowly than its surrounding townships because of the difficulty building roads through its swamplands. Its first known settlers settled in the Riversdale area in 1850. Lots along the Durham Road were surveyed first and settled in 1851. With its survey complete in 1852, it was the last township, south of the Bruce Peninsula, to be surveyed.

In 1853, when the United Townships of the County of Bruce was dissolved, the townships of Greenock and Culross remained united, with Greenock being the senior township. On January 1, 1856, the union was dissolved and the Township of Greenock existed as a separate and independent township.

Lands were not ideal for farming, the preferred occupation of most of Bruce County’s early settlers. During a large land sale in 1871, Henry Cargill purchased much of the land and built a lumber empire. The community of Cargill sprang up around him.

The Municipality of Brockton was formed on January 1, 1999, by amalgamating the township of Brant, township of Greenock and the town of Walkerton. Brockton’s name was formed as a portmanteau of the three merged municipalities (Brant Greenock Walkerton).