About 200 Hydro One employees will help local utilities in the Baltimore, Virginia and Washington areas.
Friday's storm arrived with little warning, killing 22 people and knocking out power to three million homes and businesses, so utility companies have had to wait days for extra crews.
Nearly 1.8 million people are still without electricity.
Hydro One has agreements with North American utilities to help out during significant power outages.
In February 2010, Hydro One assisted utilities in Vermont after a winter storm, and in September 2008, crews travelled to Ohio to help restore power after hurricane Ike caused major outages.
U.S. officials fear the death toll, already at 22, could climb because of the heat and widespread use of generators, which emit fumes that can be dangerous in enclosed spaces.