The 23-year-old grew up mainly in South Auckland and admits he was known for getting into trouble. Hanging out on the streets of Otara and getting up to no good was the norm.
So to come out of that life and be where he is today is still mind-boggling, he says.
"I could've been anywhere. I could've been on the streets still, begging for money. But I'm just thankful I was blessed with some really awesome people later in my life."
In 2011, an offer from a mate to take part in a professional Mixed Martial Arts showdown at the local recreation centre would change his life.
"One of the other guys had dropped out so I was a fill-in. But I went into that and got the win."
Three years on, he is under the tutelage of veteran trainer Lolo Heimuli - who has trained fighters Shane Cameron and kickboxer Ray Sefo - and is pushing towards his dream of fighting in the coveted Ultimate Fighting Championship.
Mr Ulberg is also a part-time model, a personal trainer, and recently set up the Carlos Ulberg Trust, a community trust aimed at helping to change people's lives through sport.
Late last week he was among those honoured in the inaugural I Am Auckland awards, which recognise young people doing well in the community.
The awards are run by the Auckland Council in association with The Cube, an organisation helping young people with disabilities.
Mr Ulberg said he hoped people going through tough situations would hear his story and believe they could make something of themselves.