Cameron, British Energy Secretary Ed Davey and top executives from energy company Centrica announced a 20-year deal to secure liquefied natural gas from the Sabine Pass terminal in Louisiana.
"Future gas supplies from the U.S. will help diversify our energy mix and provide British consumers with a new long-term, secure and affordable source of fuel," Cameron said Monday.
Centrica entered into an agreement with Cheniere Energy Partners to purchase around 1.75 million tons of LNG from the Sabine Pass terminal for a 20-year period.
Sabine Pass is the only terminal outside Alaska to get U.S. approval for full LNG exports. U.S. lawmakers have pressed for more export options given increased natural gas production.
Davey added that Britain was taking advantage of growing natural gas supplies from the U.S. shale boom.
Cheniere said commercial operations should start by 2015. Centrica said it expects to get its first shipment by 2018.