YouTube star JoJo Siwa and gold medal Olympian Suni Lee will compete on "Dancing With the Stars" season 30.

The two were announced at ABC's Television Critics Association presentation on Thursday as the first two celebrity contestants for the series' landmark 30th season, premiering Sept. 20.

Thirteen more celebrities will be exclusively revealed Sept. 8 live on "Good Morning America." The stars will find out which dancing pros they are partnered with during the season 30 premiere.

Siwa rose to fame on the reality TV show "Dance Moms" and is a dancer, singer, actress and YouTube personality with 12.3 million subscribers on her channel. The 18-year-old, known for her colorful outfits and big smile, came out as LGBTQ in January and later said she identifies as pansexual.

Lee, also 18, just returned from competing in Tokyo where she took home a gold medal in the all-around competition, a bronze medal for the uneven bars and a silver medal in the team competition. Lee is the first Hmong-American gymnast to compete for Team USA.

"It's very different than gymnastics but it's obviously not going to be as difficult as doing gymnastics was, so I'm really excited because I kind of just get to have fun and let loose," Lee told "GMA" Friday.

The gymnast said she recently started college at Auburn University and will be doing online classes this semester to allow her to take part in "DWTS."

VIDEO: Suni Lee and JoJo Siwa on upcoming season of ‘Dancing With the Stars’
The Olympic gymnast and YouTube star were the first celebrities announced for the upcoming 30th season, with Siwa competing as part of the show's first same-sex pairing.

This season the judging panel will consist of Len Goodman, Carrie Ann Inaba, Bruno Tonioli and Derek Hough.

Siwa to make history as 1st same-sex 'DWTS' pairing

Executive producer Andrew Llinares announced during the TCA panel that Siwa would be paired with a female pro, making it the first same-sex pairing in "DWTS" history.

"I think it's really special that not only now do I get to share with the world you get to love who you want to love, but also you get to dance with who you want to dance with," Siwa said. She added that, when presented with the opportunity to dance with a male or female partner, she jumped at the chance to be in a same-sex pairing "without hesitation."

Siwa said there is "a lot of pressure" being the first and that her journey will have its ups and downs, but she is ready for whatever comes her way, adding, "I want to make it OK for the people who come after me."

The former "Dance Moms" star said she is "really looking forward to" breaking barriers and representing the LGBTQ community and "people who feel just a little different." She also added that her girlfriend is "super pumped up" for her.

"You're making history, JoJo," host and executive producer Tyra Banks added, saying she is "so proud" of Siwa and the show for giving her the platform.

A refresh on last season

Last year, former "Bachelorette" star Kaitlyn Bristowe and Artem Chigvintsev won the coveted Mirror Ball Trophy. The pair beat out "Catfish" host Nev Schulman and Jenna Johnson as well as "Hot in Herre" rapper Nelly and Daniella Karagach to take the top spot.

Season 29 featured many firsts for "DWTS," with Banks taking over hosting duties and becoming the first Black female host -- and solo host -- in franchise history. Britt Stewart also joined as the series' first-ever Black female pro.

"Dancing With the Stars" season 30 premieres Monday, Sept. 20, on ABC.