The Cleveland Cavaliers guard won an NBA title as LeBron James' right-hand man in 2016 but has recently struggled with injuries that included a concussion that saw him miss a bulk of his eighth season.

Dellavedova confirmed his signing on Friday, but was careful to add his thanks at United's allowance for him to explore another NBA opportunity during free agency.

A move to the defending champions would be the biggest NBL coup since fellow NBA title-winner Andrew Bogut's return to the Sydney Kings in 2018.

"Melbourne is close to family and my hometown of Maryborough and I have always wanted to come back here and play at some point," he said.

"I'm glad to make the announcement today that when that time comes I'll be pulling on a United jersey.

"The NBL is a quality league that continues to evolve and has a lot of respect around the world.

"I'm excited for the challenge ... but for now there's one focus - the Boomers and winning a gold medal."

He would join Boomers teammate Chris Goulding at United, while fellow Australian teammate, replacing the Adelaide-bound Mitch McCarron at point guard.

Dellavedova will play his third Olympics in the hope of impressing NBA scouts and earning a ninth season in the league, where he's earned a reputation as a ferocious competitor, savvy playmaker and reliable shooter.

"Delly is one of the greats of our game and is also one of the most well respected and liked figures in the Australian basketball community," NBL commissioner Jeremy Loeliger said.

"Still an NBA level talent, the fact he wants to return home and continue his career here is a massive endorsement of the NBL and our standing as one of the world's best leagues outside of the NBA."

In other NBL roster movements, Illawarra's All-NBL First Team import Tyler Harvey has re-signed with Illawarra on a three-year deal, while fringe Boomers centre Isaac Humphries also confirmed a one-year extension with Adelaide.

Australian Associated Press