ET exclusively spoke with the dancer just hours after the exciting news was revealed on Tuesday, where she opened up about what it feels like to make history as the dance competition show's first Black female pro. After making several appearances on DWTS, Stewart became a full-time member of the troupe in 2016, but did not dance last year as the troupe was cut for season 28.
"It's happening!" Stewart exclaimed, telling ET she's been keeping the role a secret for about a week. "I'm just so grateful, so excited and over the moon, honestly. Ever since I found out, I just don't really know what to do with myself. So much excitement, so much emotion."
"When it set in, emotion really took over," she added. "I started crying and then immediately when I got off the Zoom call [with producers] I called my mom and I was just like, 'Ahh!' and just all the tears were flowing."
While DWTS has cast Black male pros in the past (Brandon Armstrong and Keo Motsepe will both be returning this season), season 29 with mark the first time the dance competition show has ever had a Black female compete with a celebrity partner.
"To be the first Black female pro is such an honor, and I definitely don't take it lightly," Stewart said. "Having this opportunity and position is just so beautiful. I'm so happy to take it on and also be a part of a show that celebrates diversity."
"When I was there for five seasons on troupe and two tours I always felt celebrated -- for not just my race, but for all of me," she continued. "Also, being part of Dancing With the Stars, which has that sort of love and openness for equality, is an honor as well."
"Everyone in the DWTS Twitter fandom had been wanting Britt to have a pro spot for a long time. It's natural that when a professional dancer joins troupe, they eventually get promoted to a pro spot," Chanthavisay told ET, of what inspired them to take action. "We were immensely disappointed when DWTS disbanded troupe. We felt that Britt (and Hayley Erbert as well) were robbed of their deserved opportunity to advance in the show, mainly because they had been on troupe and the tour for so many years."
"We have always been huge fans of Britt's and we thought it was about time that we spoke up and tried to make a change," Kappmeier added. "This petition was essentially made because we absolutely adore Britt, but we also wanted to shine a light on the series' lack of diversity. We were hoping it would not only help Britt get the professional spot she has rightfully earned, but that it would also become a possible gateway to allow more diversity into the show; to let more talented dancers of color have the opportunities to create on such a big platform like Dancing With the Stars."
Of all the fan support she's received over the years, especially this week, Stewart couldn't be more grateful. She thinks back to how proud her 8-year-old self would be of the woman she's become today.
"I was so happy to see my girls on Twitter create a petition. It's so sweet and so heartwarming," she gushed. "This is where I get a little emotional ... I would tell that little girl that no matter what, anything is possible, and to never be afraid to reach for the highest possibility ever."
"Sometimes you don't know how high you can reach until you get to a certain place and you see it," she added. "You see it be tangible, or you see someone that looks like you doing it and then realize it's possible."
Needless to say, Stewart's dream of becoming a pro on DWTS has been a long time coming. When ET spoke with her at Pro Dance Camp in April 2018, she said she was definitely hoping to land the job someday.
"I would love to be a pro," she said at the time. "I think that is definitely a short-term goal of mine. I don't know when it's going to happen but I have my fingers crossed that's going to happen very soon. I mean, I'm still the newest girl on the show, but Alan [Bersten] made it happen! So, yeah. Hopefully soon."
Dancing With the Stars returns Monday, Sept. 14 at 8 p.m. ET/PT on ABC. In the meantime, tune into Entertainment Tonight on Tuesday for more from Stewart's interview.