The 25-year-old will play the role of new ambulance technician Polly Emmerson, a young and very determined woman with a great talent for her job.
Polly has a lot to say and while the rest of the team can see that she's oozing with potential, the 23-year-old still has much to learn. Her passion and drive to succeed sometimes results in her becoming embroiled in the lives of her patients, while the subtlety of relationships sometimes passes her by unnoticed.
Despite her best intentions, Polly needs to come to terms with the fact that she's just one cog in the Holby City Hospital machine and can't change everything by her actions alone.
Speaking of her casting, Sophia told DS: "I feel very lucky to be joining such a long-running and well-established drama. I'm looking forward to Polly bursting onto screens, and hope viewers find her as much fun as I do."
Series producer Oliver Kent added: "Sophia is a brilliant actress and we're very excited that she's joining us. We can't wait for the audience to see her - they're going to love her."
Sophia has previously made a guest appearance in Casualty episode 'No Place Like…' playing Shauna Milsom, while her first ever acting role came in June 2004 when she portrayed Gemma Walker in an episode of Holby City entitled 'In At The Deep End'.
Her other acting credits include The Royal Today, Spooks: Code 9 and Survivors.
She began filming in December and will first appear in an episode to be broadcast on March 29.