The dance floor is getting crowded and the fans are loving it. "Dancing with the Stars" adds four more celebrities to its Season 21 lineup: Alexa and Carlos PenaVega, Vine star Hayes Grier and legendary singer Chaka Khan.

There's going to be a diverse set of dancers for the upcoming season of DWTS. Joining television personality and animal activist Bindi Irwin, renowned jockey and Triple Crown winner Victor Espinoza and Backstreet Boys' Nick Carter, are four more faces that the audience will be tuning in for.

Hollywood sweethearts Alexa and Carlos signed up for the hit dance competition and announced it on Entertainment Tonight (ET) during Alexa's 27th birthday at Disneyland's Diamond Celebration.

"It's so exciting," Alexa told ET's Cameron Mathison, expressing her excitement at the new challenge ahead for the loved-up pair. "It's beautiful, it's overwhelming, it's an incredible blessing."

The couple shared a first dance as bride and groom over a year ago, but they won't be hitting the dance floor together to chase the coveted Mirror Ball Trophy. Although their pro partners will not be announced until next week, Alexa and her 26-year-old husband will be up against each other for the competition.

There's no need to expect friction from the duo, because they're committed to enjoying the experience together even on the competitive stage of DWTS. The "Spy Kids" actress said that her husband's presence comforts and encourages her, calling him a "teammate" and "lifetime partner."

Actor and singer Carlos agreed with the sentiment. In fact, the prospect of joining the upcoming season with his wife was the main reason he was convinced to step into his dancing shoes.

"The opportunity to work with my wife was like kind of almost a number one because we love spending time together," he explained to ET. "We're almost two years married. It's still fresh. I was like, 'Babe, we got to do this' and here we are."

The fresh-faced teenager that will be joining them in their journey is Hayes Grier, as announced on the official DWTS Twitter account. The talented 15-year-old is one of the youngest celebrities to compete in DWTS, but he's not showing any nerves on social media when he tweeted on his Twitter account, "I'm excited".

After his first rehearsal as a contestant, he took to Twitter again to share his thoughts with his followers: "Dancing is fun. I've never looked at it or taken it the way I did today. First rehearsal went great. Who do you think my partner is gonna be?"

The final celebrity revelation of the week balances Grier's youthful appeal with decades of experience. Known for her distinct vocal range, Chaka Khan looks to add a new facet to her performances by showing her prowess in ballroom dancing in the upcoming DWTS season.

DWTS announced the 10-time Grammy Award winner's participation in the season with a short video clip of Khan on Twitter.

"I want you to look out for me this season on 'Dancing with the Stars,'" the powerful singer said in the teaser.

The rest of the roster and their pro partners for the upcoming season will be announced on Wednesday, September 2, on "Good Morning America".

"Dancing with the Stars" Season 21 will debut on Monday, September 14 at 8 p.m. on ABC.