It is located in the area of the city of Sarnia, in the southwest corner of the province of Ontario.

Until 2015, Sarnia—Lambton, with its predecessors Sarnia, and Lambton West, was Canada's most bellwetherly riding, having voted for the winning party from 1963 to 2011.

[3] It was created as Sarnia electoral district in 1966 from parts of Lambton West riding.

In 2003, it was redefined to consist of that part of the County of Lambton comprising the City of Sarnia, the towns of Petrolia and Plympton-Wyoming, the villages of Oil Springs and Point Edward, the townships of Enniskillen and St. Clair, and Sarnia Indian Reserve No.

Ethnic groups: 88.0% White, 5.6% Indigenous, 1.9% South Asian, 1.3% Black Languages: 90.0% English, 1.8% French Religions: 58.1% Christian (23.9% Catholic, 8.8% United Church, 5.0% Anglican, 2.9% Presbyterian, 2.8% Baptist, 1.5% Pentecostal, 1.0% Reformed, 12.3% other), 39.0% none Median income: $42,800 (2020) Average income: $55,500 (2020) Note: Conservative vote is compared to the total of the Canadian Alliance vote and Progressive Conservative vote in 2000 election.