She urged other McDonald's customers to check their food carefully after buying the meal from a drive-thru in Liverpool, Sydney.
She told 7News: 'I felt my tooth bite into something hard and thought ‘oh no this is glass’.'
Ada had bought the same burger for her niece who was also in the car, but thankfully, the little girl wasn't ready to eat it yet.
She returned to the branch and was offered a replacement, as well as a refund.
But after her near miss, Ada said she no longer had an appetite.
Sharing her photos to Facebook, Ada wrote: 'My three-year-old niece ordered a chicken & cheese as well and thank god I didn’t give it to her yet!'
A McDonald’s spokesman told 7NEWS.com.au the fast-food chain will investigate the apparent contamination.
'We are disappointed that this has happened,' he said.
'We take food safety very seriously and have strict processes and systems in place.
'An investigation is currently underway with the restaurant, and we encourage the customer to contact us to help us to investigate fully.'
