Former Conservative leader Andrew Scheer will lead the party in Parliament for the time being.
Scheer was chosen as the interim Opposition leader by party caucus members on Tuesday.
The role was needed after party leader Pierre Poilievre failed to be re-elected in his Ottawa-area riding.
Without a seat in the House of Commons, he is not able to serve as Opposition leader.
Alberta MP-elect Damian Kurek is giving up his seat so Poilievre can run in a byelection.
The Conservatives took Kurek’s riding of Battle River-Crowfoot with more than 80 per cent of the vote.
No date has been set for the byelection but Prime Minister Mark Carney said he would call one as soon as possible.