"I loved it (in New Zealand) and it is awfully bittersweet, but that is how the business works and I am positive about the decision I'm making."
It is United's first big signing of the off-season. The club is still talking to its reigning MVP Chris Goulding and remains hopeful of retaining him.
It is also understood Melbourne is speaking to Breakers big man and Guam international Tai Wesley, who has signalled his intent to leave New Zealand.
United and the Breakers saw a lot of each other in the back end of last season.
They played each other in the final two regular-season games before meeting in a best-of-three semi-finals series.
New Zealand eliminated minor premier Melbourne in straight sets and Jackson had plenty to do with that.
He is a known big-game performer, a two-time Grand Final series MVP winner and his finals experience should help Melbourne.
Jackson said he liked the look of his new team.
"You just have to look at the way they competed the previous season," he said.
"It really showed they're a big threat and capable of winning a championship.
"I felt pretty comfortable with my decision and I'm excited by the opportunity."
Jackson said he had already built a rapport with United's American coach Dean Demopoulos which convinced him to sign with Melbourne.
"We had a few conversations here and there throughout the year," he said.
"But after last season and the playoffs, I had the opportunity to talk to him a little bit and he seemed like somebody I could really relate to.
"And by that I mean a players' coach and we just had a good vibe, so that helped my decision."
- news.com.au
