Churchill Lake is a large glacial lake in the north-western part of the Canadian province of Saskatchewan. It is the source of the 1,609-kilometre (1,000 mi) long Churchill River, which flows east into Hudson Bay. Frobisher Lake flows into Churchill Lake from the north through Simonds Channel and Peter Pond Lake flows in from the east through Kisis Channel. The outflow is at the southern end through MacBeth Channel, which flows south into Lac Île-à-la-Crosse. The lake can freeze from as early as November and remain frozen till May.

The village of Buffalo Narrows is on the south-western shore near Kisis Channel and the Churchill Lake Indian reserve is at the northern end. Churchill Lake Outfitting is on the north-western shore. Access to the lake is from Highway 155 (which crosses Kisis Channel) and Buffalo Narrows Airport.

John Franklin's Coppermine Expedition map of 1819–1822 shows details of the fur trade route from Île-à-la-Crosse to the Methye Portage. Churchill Lake is shown as "Clear Lake" with its northern reaches still unknown. The upstream lakes on the map include Methye Lake (Lac La Loche) and Buffalo Lake (Peter Pond Lake). Clearwater Lake (or Clear Lake) was renamed Churchill Lake in 1944 and Buffalo Lake was renamed Peter Pond Lake in 1932.

The lake's fish species include: walleye, sauger, yellow perch, northern pike, lake trout, lake whitefish, cisco, white sucker, longnose sucker, and burbot.

• List of lakes of Saskatchewan