The company has asked the Canadian Nuclear Safety Commission to postpone a hearing in June to conclude the environmental assessment for the project.
Cameco cited poor economic conditions in world uranium markets as the reason to halt proceedings. The company also withdrew its application for a 10-year licence to build and operate Millennium.
The proposed underground mine would have capacity of up to 200,000 tons, reported Bloomberg.
Cameco said in a statement, "Cameco will continue to do some limited work related to Millennium in order to be in a position to resubmit our application should market signals indicate new uranium projects are required."
Cameco had bought 70% stake in the Millennium Mine project from Areva for $150m and received provincial approval for the development in December 2013.
