The acquisition will add more than 275,000 gas and electricity customer accounts to Direct Energy.
Centrica said that the purchase of Gateway Energy forms part of its strategic priority to build an integrated North American business.
Direct Energy president and CEO Chris Weston said competitive retail markets in the north eastern US provide the company with opportunities to grow its North American business.
"Gateway builds on the progress we’ve made in North America over the past decade and represents another important step towards our stated goal of doubling the profitability of Direct Energy," Weston said.
