Portis, who tweeted he was returning to the defending champions, became a cult hero in Milwaukee this season, averaging 11.4 points and 7.1 rebounds per game while shooting 47.1% from 3-point range in 66 games for the Bucks.
And after playing little to no role in the Eastern Conference semifinals against the Brooklyn Nets, Portis played well against both the Atlanta Hawks in the Eastern Conference finals and against the Phoenix Suns in the NBA Finals in helping Milwaukee win its first championship in a half-century.
After the Bucks clinched the title at home in Game 6 last month, Portis talked about the importance of finding a home in Milwaukee and how happy he was that he'd done so.
"I knew it was the right place when I made the decision," Portis said then of signing with Milwaukee. "I knew it was right with my agent. Fun fact, like fun little quick story. During free agency -- actually before free agency, the Knicks turned down my team option and they wanted to sign me to another deal and it was pretty nice money. But I wasn't really worried about the money. You know, sometimes money isn't everything. It's about happiness. That's one thing God taught me as a rookie: Happiness is what it is. I found happiness here. When I first got here, I felt welcome and I felt loved. The guys made me at home and the coaches made me comfortable.
"It was a nice place, easy system for me to fit in. I get to be myself every day, just be energetic. Guys on my team, they are kind of quiet guys. There's not many guys like me that are outgoing and really bring what I bring to the table with energy and things like that.
"I just thought it was a match made in heaven. I'm a guy that, whether I'm making shots or missing shots, I go out there and give 110 percent to the team. I put my body on the line every day, sacrifice. Being around these guys taught me a lot. I've learned how to win again. I haven't won in a long time, but it sure feels good now."
The Bucks will now pivot to other business this offseason as they go about defending their title. They also agreed to a one-year deal with free-agent forward Semi Ojeleye on Monday, Ojeleye's agent, Sean Kennedy of Excel Basketball, told ESPN's Adrian Wojnarowski.
The terms of Portis' agreement were first reported by The Athletic.