In 1872, the title of Cobourg Collegiate Institute (CCI) was granted.

In 1901 the cornerstone for CCI was laid at 135 King Street West, establishing the school on its own site.

With the post WWII population boom, the number of students continued to increase.

In 1961 a second high school in Cobourg was built, resulting in the splitting of original CCI into Cobourg District Collegiate West (CDCI West) at the original site, and Cobourg District Collegiate Institute East at the new site at 335 King Street East.

By 2015 the buildings at CDCI West were sold to a private school and the two public high schools were amalgamated back into CCI at the 335 King Street East site[1] [2] [3]