Ireland Nugent's legs were severed below the knee when her dad Jerry accidentally dragged her down the driveway under the mower at their family home back in April.
He hadn't noticed the toddler had run in front of the machinery as he tended to the family's Florida garden.
Ireland's legs were instantly cut off, and she was rushed to hospital where she spent several weeks being treated for her injuries and fitted with prosthetics.
As she celebrated her third birthday ahead of undergoing more surgery, her mum Nicole told the Tampa Bay Times it was more than just a party for her special day.
"It's just not her birthday to us, it's just a celebration of being here," Nicole said. "I think this is a day we will never forget."
Her dad said it was 'another moment we've been waiting for' and that it was 'great to be here with her celebrating her birthday since the accident'.
WTSP televised the plucky tot's party, which saw her dressing up as a princess and Spiderman, before tucking into cake with her friends and family.
Little Ireland is due to return to hospital this week where she will have surgery to shave down the bone on her right leg, a procedure she will have to continually endure as she grows.
She will then be fitted with new, improved prosthetics to enable her to walk more easily.
Since the devastating accident, well-wishers have donated more than $150,000 to help cover the Nugent's medical bills.