As the MailOnline reports, the 71-year-old star has been busy in London rehearsing for the film.
The singer has also teased the news, tweeting a picture of some ABBA-esque, 70s-inspired platform boots with decorative stars and a very chunky heel.
The film will mark her return to big screen after a seven-year absence — a reality that has raised the spirits of her 3.5 million Twitter followers.
It is not yet known which role Cher will play.
However, she announced the title of one song she will sing in the film.
Can you hear the drums?
The name of the song is “Fernando“. Released in 1976, it remains one of the best-selling singles, not just released by ABBA, but of all time.
Benny Andersson, formerly of ABBA, had previously confirmed the titles of three songs that would be featured in the film — “Angel Eyes“, “I Wonder (Departure)” and “When I Kissed the Teacher“.
Cher also revealed that she would have at least two dancing numbers in Mamma Mia! Here We Go Again.
“Just went through two dancing numbers, everyone’s great,” she said.
The first film Mamma Mia! (2008) was adapted from the West End musical of the same name, which in turn is based on the greatest hits performed by ABBA.
The sequel Mamma Mia! Here We Go Again is an original piece directed by Ol Parker. It will feature the original cast members Meryl Streep, Pierce Brosnan, Colin Firth, Julie Walters, Stellan Skarsgård, Christine Baranski, Amanda Seyfried and Dominic Cooper.
New additions to the cast include Cher, Downton Abbey star Lily James (who will play the younger version of Donna Sheridan, the character played by Streep), Jeremy Irvine and reportedly Andy Garcia.
Mamma Mia! Here We Go Again will see Academy Award winners Meryl Streep and Cher share the screen for the first time since Silkwood (1983).
Colin Firth, one of the main stars of the film, told Digital Spy that making Mamma Mia! was one of the “most memorable experience of his career.”
“I actually really loved [it]…I saw a journalist actually changed colour when I said that was one of my favourite things I’d done, because I think it doesn’t pass the snob test very easily.”
“But I do think it is incredibly unusual to find a piece of entertainment that hits common ground. Because, frankly, it doesn’t matter what you think of ABBA – you know it,” the Oscar-winning actor said.
His co-star Dominic Cooper did not hide his excitement about the film either.
“I thought it was going to resurface much more quickly than this, but what’s great is that they’ve waited.”
“They’ve waited for a script to come along that makes sense and is fun and is gonna be as exciting for fans of the original, and that’s really important.”
Are you excited about Mamma Mia! Here We Go Again? Do you think Cher will make a worthy cast member? Tell us in the comments section below!