The 41-year-old, who played Christian Clarke in EastEnders from 2008 until earlier this month, will play the role of Zach in Bob Avian's upcoming production.
Partridge will star opposite Singin' in the Rain actress Scarlett Strallen when the show begins at the Palladium from February 5, reports the Daily Mail.
He described the character of Zach - the director auditioning dancers for a Broadway show - as "charismatic and manipulative" and revealed that he took on the job to work with Avian, who was co-choreographer on A Chorus Line in 1975 alongside original director Michael Bennett.
"It's one of those opportunities you've got to grab," Partridge added.
The former Walford favourite recently left EastEnders along with co-star Marc Elliot, who played Christian's boyfriend Syed Masood.
Partridge said of his decision to depart the BBC soap: "I have had the time of my life at EastEnders - but I have always gone with my gut - and leaving at the same time as Marc felt like the ONLY thing to do.
"It is the right end to the story and for Christian. But also, excitingly, the start of a whole new chapter for me." Get the Inside Soap magazine on your iPhone or iPad