Toronto Hydro says electricity usage dropped 3.2% during Earth Hour celebrations, Saturday night.
The global event, first launched in Australia back 2007, took place between 8:30 P.M. and 9:30 P.M. requesting that participants turn off the lights.
In a tweet, Toronto Hydro said the decline in usage was equal to taking 36,000 homes off the grid.
PowerStream, which services municipalities around Toronto, reported a 4.3% drop in electricity consumption compared to a 6% reduction last year.
Elsewhere, Prime Minister Justin Trudeau was among millions who turned off their lights, worldwide.
A spokesman for the PM says lights were turned off at the Rideau Hall cottage where the Trudeau family is living during renovations to the official residence at 24 Sussex Drive.
Trudeau later tweeted that the forthcoming federal budget will contain steps to deal with climate change.
Tweeting about #EarthHour is one thing. Tuesday, we'll put words into action with a budget that builds a clean economy for Canada.
— Justin Trudeau (@JustinTrudeau) March 20, 2016