And when it was time for his old nemesis David Stern to hand him the shiny gold trophy, this was his big chance to say anything he wanted, with everyone watching.
So, what did he do?
He stood behind a 78-year-old man and let him take center stage, a reward for Donald Carter having founded the team 31 long years ago. He brought his wife and three kids on the podium to enjoy the moment. He even realized how corny he was being when he told his toddler son, "This could be yours".
Then, out came the Cuban most sports fans remember.
He swore in multiple TV interviews to emphasize how proud he was of his fans. He walked into a postgame news conference talking on the phone, hung up and hollered, "Did anybody inform you guys, we're the world champions?!" On his way out, he took the trophy with him and declared it was spending the night in his room.
Meet Mark Cuban 2.0 - an NBA champion who can be humble one moment, back to his raucous roots the next.
"You know, I probably won't even shower for six months," Cuban said, laughing. "My biggest fear is that I can't remember every little part of it, every emotion, every feeling that I went through as the clock was winding down ... I was just hoping I could just do an emotional videotape of myself and just keep it. So that's my biggest hope and fear that I'll be able to feel this forever."
Cuban hadn't spoken publicly since winning the Western Conference championship, when he proclaimed, "We ain't done yet!"
On Sunday night, he spoke into the microphone with a voice scratchy from screaming and choked with emotion. He talked about being happy for his players, complimenting them for having "so much heart, so much determination and so much more than that".