Nepean is a provincial electoral district that has existed from 1987 to 1999, and again since 2018.

The riding was re-created federally with the 2012 redistribution process.

That same process was followed by the Ontario government, meaning the provincial ridings follow a similar boundary division for the 2018 provincial election.

It was represented by a Liberal MPP for eight years before it was won by then 25-year-old Progressive Conservative John Baird.

In 1999, the provincial redistribution resulted in Nepean being abolished as it was split between the new Ottawa West—Nepean and Nepean—Carleton ridings.