But most homeowners will see only a modest increase, according to Qulliq Energy spokesman Eddie Rideout.
"The difference in what a customer was paying, say, in February-March of this year, compared to what they'll pay in April, is actually quite marginal," Rideout told CBC News.
"For the average customer, I guess it'd be about $7 a month."
The 18.9 per cent rate hike will replace a six per cent interim increase that came into effect in October, so residential customers should see a net increase of just 2 1/2 per cent, according to Qulliq Energy.
Qulliq Energy is facing a $13-million revenue shortfall this year, and it needs to replace or upgrade several power plants around the territory, Rideout said.
"This increase will bring our revenue in line with our expenses," Lorne Kusugak, the minister responsible for Qulliq Energy, said in a release.
"This provides a true indicator to our customers of the true cost of their energy."
The Nunavut government is giving Qulliq Energy a cash infusion to balance its books this year, so it won't have to recoup the revenue shortfall from customers, according to officials.