"Man, I had a connection with a lot of guys here," Johnson said prior to playing at Madison Square Garden with his new team. "D-Wade, [Amar'e Stoudemire], UD [Udonis Haslem], guys I've been in contact with. Not just throughout this process, but over the years, and I just felt it was right."
Johnson, 34, had Miami, the Cleveland Cavaliers and Atlanta Hawks among his finalists, according to ESPN's Marc Stein. However, league sources said Johnson had his mind set on Miami not long after he worked a buyout with the Brooklyn Nets last week.
"I think we've got a lot of veteran guys who know what it takes to win," Johnson said of the Heat. "[And the possibility of remaining with the Heat] was another key thing for me. I would love to finish my career here. Let's see what happens."
Johnson, who averaged 11.8 points, 3.9 rebounds and 4.1 assists in Brooklyn this season, had dinner with Heat coach Erik Spoelstra and Wade on Saturday.
"The skill set that he has fits very much," Spoelstra said. "He can play a lot of different positions. ... just fit in. Be aggressive. Be who you are. We'll adapt to him."
"We've brought him here to play a significant piece to what we're trying to do," Spoelstra said. "We're in a very competitive race right now in the Eastern Conference ... to be able to add a player of his caliber, we need him in the mix. We can fast-track it."
Johnson was making $24.9 million in the final year of his six-year, $124 million max contract -- the NBA's biggest contract when he signed it in 2010 -- before the buyout.
"For me, this is my 15th season," Johnson said when asked why he changed his mind and asked for a buyout from the Nets. "So if I had a chance to get out and get a chance to play with a playoff-contending team, obviously I looked into it."