The 25-year-old Irving called playing three seasons with James as "awesome" and told reporters at his introductory press conference in Boston that "I learned so much from that guy."
The Celtics formally introduced Irving on Friday at TD Garden after the blockbuster trade sent Isaiah Thomas, Jae Crowder, Ante Zizic, the Brooklyn Nets' 2018 first-round pick and the Miami Heat's 2020 second-round pick in exchange for the four-time All-Star point guard.
Irving, who had requested a trade in July, was asked about his decision to leave Cleveland and the status of his relationship with James.
"I haven't spoken to (James) and my intent (in asking for a trade), like I said, was for my best intentions," Irving said. "To look back at the amount of ground we covered in the last three-year span ... to really realize how special that was and how much stuff happened in that amount of time, I'd be sitting up here and telling you guys a lie if I didn't tell you I learned so much from that guy.
"The perfection of the craft comes in a variety of forms. And you watch, you ask a lot of the great players, 'What does it take to be great?' I've had the unique opportunity to play with one of the greats and it was awesome. At times it was all over, just like it is in any other team, and when you look back and you're eternally grateful for the moments that you had and you shared, you're able to put peace with that journey and start anew."
A relaxed Irving said he was excited to get started in Boston.
"I can't wait to get on the floor and maximize my potential," Irving told reporters. "I just want to be around those incredible coaches and those incredible minds and those incredible individuals, and I feel like in doing that, Boston came right at the exact time and it was meant to be that way. I trust in that, and I'm glad to be here."
Irving averaged a career-high 25.2 points on 47.3 percent shooting and 5.8 assists last season. He has three years and $60 million remaining on his contract.
"It was my time to do what was best for me in terms of my intentions, and that's going after something bigger than myself, and obviously being in an environment that was conducive for my potential," Irving said Friday. "I think that statement is just self-explanatory, because it's pretty direct in terms of what my intent is -- it's to be happy and be with a group of individuals that I can grow with. That's not a knock on anything that has transpired in my six years (in Cleveland), because it was an unbelievable experience. To think about what we accomplished in Cleveland and individually as well, it bypasses the amount of moments I had with all the special people out there.
"Me leaving there wasn't about basketball, it was more or less about creating that foundation of me in Cleveland, and then now taking this next step as a 25-year-old evolving man and being the best basketball player I can be."