The retailer has signed a five-figure deal that will see its name appear on the team's shirts for the next two years, across all of the national sides from Under-16s and upwards.
The Co-operative has 450 outlets in Scotland and employs 8,000 staff there.
Liz Matkin, sponsorship manager, said: "The players and management have achieved a remarkable feat in qualifying for the World Cup in Australia later this year and we are delighted to be involved with them.
"In addition to supporting the national side on an international scale, we are also committed to the sport at community level, which is where our sponsorship has its greatest synergy."
The Rugby League World Cup begins on October 25.