Gemma Claxton, from Chapeltown, had given the Easter treats to her 13-month-old son Akelle when she discovered the bone inside the bread.
She had bought the 65p pack of own-brand hot cross buns from the Tesco store on Roundhay Road.
"I only found it when my son was pulling it out of his mouth with the bread stuck to it. He could have choked if I wasn’t watching him. Supermarkets should seriously have to tighten up food control," said Gemma.
Tesco told her to return the buns to the store and promised to investigate, but Gemma claims she has not heard back from them.
A statement from Tesco said:
We have robust measures in place to ensure our products are of the highest standards, so we would be surprised if this is an animal bone. We’ve asked Gemma to return the product to store so we can investigate with our supplier.”