Sarnia—Lambton is a provincial electoral district in southwestern Ontario, Canada.

It elects one member to the Legislative Assembly of Ontario.

From 1999 to 2007, the riding consisted of the municipalities of Sarnia, Point Edward, St. Clair and Sarnia 45.

For the 2007 election, it gained the municipalities of Petrolia, Plympton-Wyoming, Oil Springs and Enniskillen.

^ Change is from redistributed results Swing: 4.80% from PC to Lib (Lib hold)