The Fashion Star presenter claimed to be feeling broody two weeks after the birth of her niece.
The 27-year-old's brother Jack Osbourne witnessed his first child with Lisa Stelly being born late last month, and his sister has now revealed that she has the baby bug.
She told Anderson Cooper on Anderson: "I've got baby fever after I saw [her]. I'd be the best mum ever. I would. I've got great training from my mum."
The star even admitted that the latest edition to the Osbourne family, Pearl Clementine, has opened up her mind to new beliefs.
She said: "I have to tell you, I never believed in love at first sight. And then when I saw how perfect and beautiful this baby was and is, I lost it. I cried more than anyone else."
As a first time aunt, Kelly also said that she has been warned not to lavish the child with treats, although she is unsure whether she'll be able to resist.
She added: "I'm under strict instruction not to spoil her but I don't think that's going to stick."
Watch Kelly Osbourne on Anderson below: