Among the items up for grabs is a Toronto Maple Leafs comforter, a matching pillowcase and a pair of size 7 Nike high-top shoes.
"At Christmastime, Justin autographed each item for us, and we made a certificate of authenticity that his grandmother signed," said Theresa McMurray, executive director of the Stratford House of Blessing, which runs a food bank and offers help to those in need socially, spiritually, physically and economically.
It was Bieber's grandmother who came up with the idea of auctioning off her grandson's possessions on eBay for charity.
"When they put their house up for sale, they had people inquire with them as to buying some of the items they saw in Justin's bedroom," McMurray said.
"They thought, 'This would be a great idea to not only support a local charity, but also to give Justin's fans the opportunity of owning some of his childhood items.'"
McMurray said the family chose to donate the proceeds of the auction to the House of Blessing because when he was a child, Bieber and his mom used some of the charity's services.
"This is the way they want to give back to the community ... so that others can be helped in the same way," she said.
As well as the food bank, the House of Blessing offers cooking classes, life skills workshops and a Christmas toy drive.
The auction will close at noon on Saturday, Feb. 7.