Jamie Lynn Spears, Tyson Beckford join 'Dancing With the Stars'

“The Brady Bunch” star Barry Williams and Oscar-winning actress Mira Sorvino have joined the “Dancing With the Stars” cast for Season 32.

Williams, 68, who played oldest brother Greg Brady in the iconic TV series, and Sorvino, 55, an Oscar winner who last starred in the drama "Sound of Freedom," were announced along with the full “DWTS” cast Wednesday on “Good Morning America.”

"Zoey 101" star Jamie Lynn Spears, “Vanderpump Rules” personality Ariana Madix and “The Bachelorette” star Charity Lawson had already been revealed as contestants in the reality ballroom competition. Read on for the full list of competitors.

After a year of streaming exclusively on Disney+, “DWTS” returns to ABC on Sept. 26 (8 EDT/PDT), also the anniversary of the first "The Brady Bunch" episode in 1969.

"That's a date that has a very large connection to 'The Brady Bunch,'" Williams tells USA TODAY while discussing his "DWTS" chances.

Barry Williams promised late 'Brady Bunch' mom Florence Henderson to 'Keep on Movin' on 'DWTS'

Williams is the third "Brady Bunch" cast member on "DWTS." Florence Henderson, the TV family matriarch who died in 2016, competed in 2010's 11th season, and her screen daughter Maureen McCormick (Marcia Brady) competed in 2016's Season 23.

"The producers finally decided to get the 'Brady Bunch' guys represented," Williams says. "Florence was very encouraging about it. She told me, 'Promise me, if I don't win, that you'll go all the way if you ever do the show.'"

Starring in Broadway stage and touring productions, Williams has dance experience and training. And he famously showed moves performing "Keep On Movin" with his TV siblings in a fan-beloved 1973 "Brady Bunch" talent show episode.

"That helps create very low expectations," Williams says. "We had to choreograph to our lowest common denominator in order to make everyone look good. But still, I'll have to work doubly hard to come up to par."

At his age, Williams has to be "very careful" with the strenuous workload and routines, even in rehearsal. "I do an extended stretching routine regimen every day and make sure I rest. This show is very demanding," he says. "But I feel absolutely great."

His wife, Tina Mahina, has already built a Mirrorball Trophy shelf in the living room of their Branson, Missouri home. "She told me the shelf is for 'my trophy.' I love how she calls it her trophy," says Williams, who is paired with pro partner Peta Murgatroyd. "This show is a tremendous commitment. I literally moved my life to Los Angeles for three months and we're working seven days a week. I'm totally focused."

The "DWTS" casting has been such a secret that even longtime friend Christopher Knight, who played Peter Brady and is Williams' partner on The Real Brady Bros podcast, was kept in the dark. But Williams is counting on his "Brady Bunch" TV family and fan support to help him win the voting half of the competition.

"I will be enrolling all the fans I can reach, and hopefully we can make a powerful Brady Bunch Nation."

Mira Sorvino says her father, 'Goodfellas' actor Paul Sorvino, would be 'proud'

Sorvino, who won the Best Supporting Actress Oscar for the 1995 Woody Allen comedy "Mighty Aphrodite" and who danced silly with Lisa Kudrow in the 1997 comedy "Romy and Michele's High School Reunion," is looking forward to perfecting her ballroom skills on "DWTS" with pro partner Gleb Savchenko.

"This is my year of trying things that I love but hadn't dared to do," Sorvino says. "I'm so excited to make believe for three months that I'm an actual dancer."

The elaborate "DWTS" costumes help the fantasy world, and Sorvino was blown away by the first wardrobe fitting.

"I saw all the sequins and bedazzled dresses, the feathers, everything hanging from these racks. It was like a fantasy world, a little girl's dream dress-up closet with the glitziest, most glittery dresses."

Getting to dance perfection will take plain hard work. Sorvino has salsa dance experience and had formal ballet training until age 14.

"That helps for sure, you engage your body and learn choreography," she says. "But this is a really different world, and the salsa is really different from the cha-cha. So it's all fun and scary and awesome."

Actor/director husband Christopher Backus and the couple's two daughters are thrilled for Sorvino's new challenge. Likewise, her Fred Astaire-loving father, actor Paul Sorvino, who died last year, "would be proud, excited and nervous." she says. The "Goodfellas" star is also an inspiration for more dance practice.

"My father was artistically judgmental. I have to work to meet his standards, in everything I do."

Who is on 'DWTS' season 32? Alyson Hannigan, Adrian Peterson, Jason Mraz

Here's the full pairing of contestants, with professional partners:

"American Pie" and "How I Met Your Mother" star Alyson Hannigan with partner Sasha Farber

Reality TV star Harry Jowsey ("Too Hot to Handle") with partner Rylee Arnold

NFL running back Adrian Peterson with partner Britt Stewart

Supermodel Tyson Beckford with partner Jenna Johnson

"I'm Yours" singer Jason Mraz with partner Daniella Karagach

Former “Bachelorette” Charity Lawson with partner Artem Chigvintsev

Marvel star Xochitl Gomez with partner Val Chmerkovskiy

“Vanderpump Rules" star Ariana Madix with partner Pasha Pashkov

Actress Mira Sorvino with partner Gleb Savchenko

Actress Jamie Lynn Spears with partner Alan Bersten

YouTuber Lele Pons with partner Brandon Armstrong

“The Brady Bunch” star Barry Williams with partner Peta Murgatroyd

"Veep" star Matt Walsh with partner Koko Iwasaki

Real Housewives of Beverly Hills" star Mauricio Umansky with partner Emma Slater

This article originally appeared on USA TODAY: Matt Walsh, Harry Jowsey join 'Dancing With the Stars' Season 32