The trio, alongside Helena Bonham Carter, Emilia Fox and Twiggy, have autographed a series of ornaments as part of the Show You Care With The Lindt Bear campaign.
The drive aims to raise $160,000 (£100,000) for the U.K. annual charity event Children in Need by putting the signed lots on internet auction site eBay.com.
Jessie J says, "The Show You Care With The Lindt Bear campaign is a great way to raise money for BBC Children in Need, it's a great charity.
"I was so happy to be able to be involved to help raise funds. Make sure you go online and get bidding! And eat lots of chocolate!"
The current highest bid is for Imbruglia's bear, which stood at $120 (£75) as we went to press. The bears will be auctioned off in phases over the course of five weeks, with the final auction closing in mid-November.