Sunday night's Ed Sheeran concert at Mt Smart prevented Warriors staff from gaining access to the club's headquarters to store playing gear and other equipment, including GPS trackers and game jerseys, after returning from Canberra.
They were forced to temporarily stash it away in an unmarked van outside a staff member's home on Auckland's North Shore, where it was pillaged overnight.
Warriors CEO Cameron George said they were "devastated" by the turn of events.
"All the playing jerseys from our historic win over the Raiders have been stolen and they obviously hold special significance for the guys," George said on the team's website.
The New Zealand side went to the top of the NRL ladder with their scintillating last-gasp win over the Raiders on Saturday, marking the first time in club history they've opened a season with three consecutive wins.
"It's taken the gloss off what was an incredible weekend, but it's just another challenge and one we are certainly not going to let distract us from making our fans even prouder in the coming weeks."
George is reaching out to the public for help in tracking down their stolen goods.
"We think someone might have followed the van all the way home," he said.
"But we've got a massive fanbase and we are hoping our supporters can keep their eyes peeled in case any of this special gear ends up for sale.
"The police have been notified and we are confident that we will be able to get our gear back."
The Warriors travel to Sydney next Saturday to take on the Roosters.