The film also stars Jonathan Bailey, Ethan Slater, Bowen Yang, Michelle Yeoh and Jeff Goldblum.
Chu told entertainment news outlet Deadline that he approached Domingo for the role of the Cowardly Lion on Instagram.
"I was like, 'It's not a ton of lines, but maybe you have a little time. I know you're busy. I'll come to you,'" Chu said, according to Deadline. Domingo responded "Why the f--- not. Let's go," he recalled.
The Broadway superstar has been nominated twice for an Academy Award, and has won a Primetime Emmy Award. He was named one of the 100 most influential people in the world in 2024 by Time Magazine.
Buzz has been growing around the sequel Wicked: For Good since the first film was released in November 2024. The first full-length trailer for the sequel was unveiled in June.
The sequel picks up where the first film left off and covers the years after Elphaba and Glinda's decision to part ways.
Elphaba is now an enemy of the state of Oz, while Glinda has become a public figure controlled by the Wizard, who is played by Goldblum.
The film's trailer also teases the arrival of Dorothy - seen walking down the yellow brick road with her friends - suggesting the character might have a bigger role in the films than in the musical. It's still unclear who might be cast to play the character.
The films have been adapted from the hugely successful Broadway and West End musical, which itself was based on Gregory Maguire's 1995 novel.
The two movies were shot simultaneously at Sky Studios Elstree in the United Kingdon between December 2022 and January 2024, with production interrupted mid-way through by the Hollywood actors' strike.
Wicked was the highest-grossing movie of 2024 in the UK, and scored 10 Oscar nominations - winning two for best costume and production design.
The sequel movie is set to be released almost a year-to-the-date of its predecessor on 21 November.
