He said the Mount Maunganui Lifeguard Service was also not aware of it being used recently.
It cost the company about $2500 to buy one defibrillator, he said.
"We are at a real loss. It's really sad from a community point of view - because this has been used six times. And now there's nothing there, which is really scary," he said.
"For this to happen is gut-wrenching. So many people have used it, or potentially could use it. It's really sad somebody has taken it."
Burnette said a report was filed with police about the missing defibrillator on Thursday morning.
He urged any community members who could provide information about the missing item to contact the company on 0800 25 25 00.
"No questions asked, no matter where it is, we will go and find it. We are relying now on members of the public."
A Tauranga City Council spokeswoman said it was supporting Exceed where possible to seek more information for the return of the defibrillator.