The former I'm A Celebrity winner is one of the celebrity cast signed up to the ITV show, which sees famous faces take on some of the biggest hits of the West End and Broadway in a special one-night performance.
Jossa is seen for the first time here in full costume as Elsa as she gives her interpretation of Frozen the Musical.
Show host John Barrowman said: "Jacqueline Jossa – the Queen of the jungle, let’s just say she becomes the queen of the night in her performance – she is regal and elegant and surprises everybody because who knew she could sing?"
The sneak peek photos also include Michaela Strachan showing off her dance moves in what looks like a tap routine, and Coronation Street's Lisa George in costume for Cabaret.
Good Morning Britain's Alex Beresford features in a performance from hit show Hamilton, while Colin Salmon takes on the grand dame of musicals, Les Miserables.
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Hamilton star Trevor Dion Nicholas said of Beresford's performance: "The song he has picked is a beast. It’s a lot of words, it’s a lot to carry across and it’s an easy one to be overwhelmed by and so I think that this is another point of excitement for me to see that go down."
Rugby player Danny Care also undergoes a complete transformation as he dons a showman's three-piece suit and tails for his song.
The celebrities will be mentored by big name musical stars Elaine Paige, Samantha Barks and Trevor Dion Nicholas, and will perform their showstopping numbers backed by a full West End orchestra with chorus and dancers.
Previous series of the show have featured former Strictly Come Dancing pro Kevin Clifton, comedian and TV presenter Joel Dommett, garden guru Alan Titchmarsh and Only Fools and Horses star Tessa Peake-Jones.
All Star Musicals has also announced its air date - it will be on TV on Sunday, 3 April at 7.30pm on ITV.
Watch: Jacqueline Jossa braves Lego brick walk challenge for Red Nose Day