The XXL cat is three years old, weighs 14kg and measures 1.2m long
Omar was the same size as all the other kittens in his litter when he was taken home by his owner Stephy Hirst.
But, now the 3ft 11in feline could be the worlds longest feline in the world.
"We realised when he got to 10 kilograms before the age of 1 that he was probably going to be impressively large," Hirst told Moncrieff.
"We decided to Google 'the longest cat in the world' and we found the current holder, and the living longest cat, and we thought we would just pull out the measuring tape and see how Omar compared."
Omar currently weighs 14 kilograms. He enjoys sitting on his owner's lap, though Hirst admitted only the front part of his body tends to fit.
"We buy dog beds for him because he doesn't fit in little cat boxes," she said.
Despite his size, Hirst said Omar isn't a massive eater - rather, he's more averse to exercise. His diet is carefully managed, getting a small amount of kibble and kangaroo a day.
"Our breeder suggested we incorporate some kind of raw meat in his diet," Hirst continued. "We tried chicken and beef, and the usual kind and he turned his nose up at them.
"As a last resort, I bought kangaroo meat from the supermarket and he hasn't looked back since."
With his following on Instagram ever increasing, Omar is struggling to adjust to his new lifestyle.
"He does not enjoy the fame at all. We had camera crews over at our house today, and he did not want to be on film.
"He hid from the cameras, and it took a load of coaxing for him to actually be on television."
I'm not very impressed with mum letting these camera crews invade my home, but at least I have my little brother watching my back 🐾 @penny_and_rafi . . . . #mainecoon #mainecoonsofinstagram #catsofaustralia #instacats #gingercat #overnightcelebrity #mediastar
A post shared by Omar the Maine Coon (@omar_mainecoon) on
Omar's appearance still shocks people who visit Hirst's home.
"I don't think anyone's ever prepared for the sight of Omar in person, even when they have seen photos of him. They come over to our house and he'll come creeping out and it's like 'oh my God, look at that cat'."
No vet has concluded what might have contributed to the Maine Coon's unusual size. As a result, Hirst has to be mindful of the cat's weight, and the pressure he puts on his joints.
Hirst has applied to the Guinness Book of Records to see if Omar qualifies as the longest cat in the world.