Derek Hough couldn't be happier for his "Dancing With the Stars" co-star and friend, Mark Ballas.

After ET broke the news that Ballas wouldn't be returning as a pro on season 23 of the dance competition show -- he's heading to New York City to star in Broadway's "Jersey Boys!" -- Hough admitted he was in tears over his pal's exciting new gig.

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"It's like a dream come true for him for sure, and I honestly cried when I found out," Hough exclusively told ET's Cameron Mathison at the 101 Dance Center in Los Angeles last week. "I teared up because I just know how much this means to him and he is so excited and it's awesome."

Ballas isn't the first pro to head to Broadway, and was hoping to have a friend in the Big Apple.

"It's actually funny like, Mark called me, and he goes, 'Derek, dude, I got this role' and I was like, 'We are going to be on Broadway together man,'" Hough shared.

Hough is scheduled to star as Don Lockwood in Broadway's "Singing in the Rain," but told ET it's been postponed until late next year.

"I was like, 'Dude, it has been postponed, we are doing it -- it's now like, late next year,'" Hough explained. "He was like, 'Dang, man!' But it's so great."

WATCH: Derek Hough Is Broadway Bound!

Last week, a source told ET that Ballas is moving to New York City this month, where he'll reside for a year in order to appear in a main role in the musical production. He confirmed the news on Tuesday in an excited tweet.

"THRILLED to announce I'll be playing the final 'Frankie Valli' in @JerseyBoysInfo on Broadway starting Oct 18th till Jan 15th," Ballas wrote. "See U there."

The 30-year-old dancer also hinted at his new career last Tuesday, posting a heartfelt, handwritten message to his fans via Instagram.

"I wanted to hand write this letter to personally thank each and every one of you for the support over the years," he shared. "I am incredibly moved and grateful for all your messages over the past 24 hours. I know many of you are concerned and curious. I want to wish my 'DWTS' comrades luck this season."

"I'll miss competing and creating outside the box," he continued. "However I am looking forward to this new chapter and venture that is beginning shortly. I will soon have news for you all on where you can find me, I hope to see many of you there."

WATCH: Why Mark Ballas Said No to Returning to 'Dancing With the Stars'

"Dancing With the Stars" premieres Monday, Sept. 12 on ABC.