"He's mega talented and he's my friend and he's cool and I love him," Levine gushed of the 27-year-old "Attention" singer.
"I would say all the same things, too. I genuinely mean that," Puth concurred. "... What's really awesome about Adam is that he has a great musical ear. I call him, like, the best A&R in the music industry. He has a great idea of, like, who should be paired with who and makes great suggestions."
"I'm just along for the ride," Puth added. "It's kind of nice to see everything unfold in front of me and watch him make suggestions and I throw something in too."
The duo have been friends for years after meeting while driving on California's Pacific Coast Highway. Levine and Puth spotted each other, rolled down their windows and agreed to meet for lunch.
"Then he let me borrow his sweatshirt and I stole it," Levine confessed. "... Half your stuff is at my house."
"And half your stuff is at my house," Puth added.
"Sleepovers!" Levine joked.
Puth and Levine's real-life friendship is clearly evident, but Levine assured fans that "nothing" could change his bromance with fellow Voice coach, Blake Shelton.
"Nothing could ever get in the way of my love for Blake Shelton," Levine said, before jokingly amending, "Sexual love for Blake Shelton... and hate. It's kind of a cross in between both."
Puth jumped in to confirm that Shelton and Levine's onscreen persona isn't just for the cameras, but rather a clear representation of their real-life relationship.
"I want people to know that this actually isn't just for TV, like, they actually do have, like, a nice little rivalry," Puth revealed. "It goes on on- and off-camera too."
"Also I really don't like Blake," Levine added.
"I'm trying to smooth that over," Puth jokingly chastised.
"I don't like him," Levine responded. "He's a jerk."
During the sit-down, Levine also opened up about John Legend, The Voice's new coach for season 16.
"John's great. I've known John a long time and [his] mega talent [is] awesome," Levine praised. "[He's the] easiest guy to get along with on the planet. Absolutely [the] greatest."
"John is a much more extroverted person than people realize 'cause he's so smooth and kind of mellow and serene in a lot of ways, but he went at it during the Blind Auditions," Levine revealed. "He came out of his shell and he's not that low-key, which I love... He's hysterical and I got to sit next to him, which was great."
"I was very happy when I heard he was gonna be joining," Levine continued. "I hope he wins... if it's not me, I hope it's John."
Levine wasn't shy about his love for Legend's wife, Chrissy Teigen, either!
"I love Chrissy," Levine said. "Now, that is a woman that has a very big, extroverted personality and that's kind of why you feel like John is mellower, like they kind of balance each other out, but no. John's got fire. He's got some Chrissy in him."
In addition to The Voice, Levine is hard at work on a new songwriting show, Songland, which he called "so authentic."
"I watched how great it was and I watched how real and raw it was," Levine said of the show's pilot. "... They're really doing things that you would do when you're in the studio kind of crafting a pop song. It's a fascinating look at how it goes down... It's creativity just on camera. It's very real. It's very special 'cause there's really nothing like it. I think people are gonna really enjoy it 'cause they've never seen it from this particular angle before."
The Voice premieres Feb. 25 at 8/7 central on NBC.