Maddie Ziegler is officially leaving 'Dance Moms' to star in film directed by Sia
VENICE, ITALY - SEPTEMBER 03: Singer Sia attends a photocall for 'Women's Tales' during the 72nd Venice Film Festival on September 3, 2015 in Venice, Italy. (Photo by Venturelli/WireImage)
LONDON - NOVEMBER 2001: Australian singer Sia Furler, of Zero 7, is pictured at 93ft East in November 2001 in London, England. (Photo by Jim Dyson/Getty Images)
LONDON - JUNE 3: Singer Sia Furler of Zero 7 performs live on stage at the Shepherds Bush Empire on June 3, 2006 in London England. (Photo by Simone Joyner/Getty Images)
NEW YORK - JANUARY 09: Singer SIA appears at Virgin Megastore Union Square to perform and sign autographs on January 9, 2008 in New York City. (Photo by Bryan Bedder/Getty Images)
INDIO, CA - APRIL 27: Singer Sia Furler performs during day 3 of the Coachella Valley Music and Arts Festival held at the Empire Polo Field on April 27, 2008 in Indio, California. (Photo by Dove Shore/Getty Images)
Singer Sia poses at the Vodafone MTV Australia Awards 2009 at the Sydney Convention and Exhibition Centre, Darling Harbour on March 27, 2009 in Sydney, Australia. (Photo by Mike Flokis/WireImage)
NEW YORK - AUGUST 12: Singer Sia attends Bust Magazine's 15 years of independent publishing birhtday party at Pier 17 South Street Seaport on August 12, 2008 in New York City. (Photo by Amy Sussman/Getty Images)
BERLIN - APRIL 29: Sia Furler of Australia performs at the Postbahnhof on April 29, 2009 in Berlin, Germany. (Photo by Jakubaszek/Getty Images)
NEW YORK - JULY 15: Singer Sia attends the performance of Beirut as part of the Dark Sounds Concert Series at the Solomon R. Guggenheim Museum on July 15, 2010 in New York City. (Photo by Roger Kisby/Getty Images)
NEW YORK, NY - SEPTEMBER 12: Singer Sia Furler attends the J. Mendel Spring 2013 fashion show during Mercedes-Benz Fashion Week at The Theatre at Lincoln Center on September 12, 2012 in New York City. (Photo by Stephen Lovekin/Getty Images for Mercedes-Benz Fashion Week)
NEW YORK, NY - OCTOBER 15: Singer Sia Furler attends the 2012 Building Dreams For Kids Gala at The New York Marriott Marquis on October 15, 2012 in New York City. (Photo by Desiree Navarro/WireImage)
HOLLYWOOD, CA - DECEMBER 08: Singer Sia performs onstage at 'TrevorLIVE LA' honoring Jane Lynch and Toyota for the Trevor Project at Hollywood Palladium on December 8, 2013 in Hollywood, California. (Photo by Frederick M. Brown/Getty Images for Trevor Project)
NEW YORK, NY - JUNE 04: Singer-songwriter Sia attends the 2014 Wayuu Taya Gala Honoring Kimora Lee Simmons at Trump SoHo on June 4, 2014 in New York City. (Photo by Monica Schipper/Getty Images)
NEW YORK, NY - DECEMBER 07: Singer-songwriter Sia attends the 'Annie' world premiere at Ziegfeld Theater on December 7, 2014 in New York City. (Photo by Jim Spellman/WireImage)
LOS ANGELES, CA - FEBRUARY 08: Dancer Maddie Ziegler (L) and singer/songwriter Sia attend The 57th Annual GRAMMY Awards at the STAPLES Center on February 8, 2015 in Los Angeles, California. (Photo by Jeff Vespa/WireImage)
BEVERLY HILLS, CA - FEBRUARY 22: Singer Sia arrives at the 2015 Vanity Fair Oscar Party Hosted By Graydon Carter at Wallis Annenberg Center for the Performing Arts on February 22, 2015 in Beverly Hills, California. (Photo by Axelle/Bauer-Griffin/FilmMagic)
LOS ANGELES, CA - MAY 09: Singer Sia performs onstage during 102.7 KIIS FM's 2015 Wango Tango at StubHub Center on May 9, 2015 in Los Angeles, California. (Photo by Kevin Winter/Getty Images For 102.7 KIIS FM's Wango Tango)
SATURDAY NIGHT LIVE -- 'Donald Trump' Episode 1687 -- Pictured: Musical guest Sia performs on November 7, 2015 -- (Photo by: Dana Edelson/NBC/NBCU Photo Bank via Getty Images)
According to the source, Ziegler's mom announced the news to the rest of the cast on Wednesday during a taping of the hit Lifetime reality show.
But this won't be the last you'll be seeing of the petite Pittsburgh, Pennsylvania, native -- she's set to star in Sister, a film project written and directed by her frequent collaborator, Sia.
Ziegler has already been featured in three of Sia's music videos, showing off her highly-impressive dance skills in "Chandelier," "Elastic Heart" and "Big Girls Cry." Now, the dancer will star in the singer-songwriter's first-ever film, which is based on a one-page story she penned eight years ago.
"I was too embarrassed to tell anyone I wanted to make a movie because I thought it would be seen as a vanity project because I was a singer," Sia, 40, told The Hollywood Reporter last November. "And then last year, after I made the 'Chandelier' video, I realized that I was pretty good at directing, so I felt a little bit braver."
Last September, ET chatted with Ziegler, who couldn't help herself from gushing with excitement over moving on to "bigger and better things."
"I definitely want to be moving more into acting," she explained. "Still keeping up my dancing, but also [do] movies and scripted TV shows."
She also told ET that when she met Sia for the first time, they became instant friends. "She's literally the sweetest person ever," Ziegler said. "I feel like I'm just so comfortable with her every time I'm with her. I never feel like, 'Oh my god, I'm hanging out with a celebrity.'"
"She's the most humble person and so caring, and she like, cooks for me!" she continued. "She's such an amazing person."