Bieber, 19, gave the hamster as present to Tori at an event in December 2012. The animal is said to have died of chronic renal failure. Tori buried the hamster in the garden and later posted the news on Twitter, reports thesun.co.uk.
"It's very peaceful there. He was our baby, your baby Justin Bieber. I still can't thank you enough," she wrote. Her tweet was followed by sympathetic messages from Bieber fans around the world.