The Southsea venue has teamed up with Italian theatre Teatro Nuovo Verona to stage the Shakespeare tragedy in Verona, Italy later this year.
And The Kings held auditions in a bid to find top actors and actresses to play the lead roles.
Stephanie, of Emsworth, is celebrating after being named Juliet for the production.
The 21-year-old, who is soon to graduate from Guildford School of Acting, said: ‘It’s incredible.
‘It’s a double honour because there’s the fact I get to play the part of Juliet, which is the most iconic role any young actress can play, but then there is the prospect of performing in Verona.
‘It’s a once-in-a-lifetime opportunity.
‘Plus I also get to perform in conjunction with The Kings, which is fantastic because I grew up coming to performances here.
‘So it makes it even more special.
‘It’s one of those things where I have always wanted to act since I was a little girl.’
Stephanie, who went to Oaklands Catholic School in Waterlooville, cruised through the audition stages after wowing judges with her Shakespearian monologue and performance of a scene in Romeo and Juliet.
The theatre is still yet to decide who will play that part.
And Stephanie is now preparing for a week’s worth of rehearsals in July – before preparing to perform in front of crowds in Italy later this year.
The production will be staged in Verona’s unique setting of Juliet’s Courtyard – which Stephanie says will be a ‘sensational’ experience.
Following its run in Verona, the production will be brought to the UK and the first performance will be in Portsmouth.
Paolo Valerio, artistic director of Teatro Nuovo-Verona, said he was delighted Stephanie had landed the role – and cannot wait to see her delight crowds.
He said: ‘I am very happy because Stephanie is a very, very nice actress and a nice person.
‘I know for us and for her it will be a great summer.
‘Our show is rather special.’
For further information about the international project, visit kingsportsmouth.co.uk