The Call The Midwife actress joins a jam-packed lineup that includes Peter Andre, Georgia May Foote, Daniel O'Donnell and Jamelia.
Helen admitted she's "slightly terrified" about dancing for an audience of millions, but is focusing on the upside: "I can't wait to get my tan and sequins on!"
Before landing her role in Call The Midwife, she studied at the Birmingham School of Acting and the Royal Academy of Music. She's appeared in West End shows including Woman In White. Oh, and also sang backing vocals for Sir Elton John at Wembley and the Royal Albert Hall!
Helen - who plays Trixie in BBC One's Call The Midwife - has already got into the dancing spirit, sharing an image of herself to Instagram this evening with the caption: "In honour of joining this year's Strictly Come Dancing, I've got my leg warmers on!"
Other celebrities already confirmed for Strictly Come Dancing this year include television presenter Anita Rani, The Wanted's Jay McGuiness, broadcaster Jeremy Vine, chef Ainsley Harriott, EastEnders actress Kellie Bright, Corrie star Georgia May Foote, presenter Katie Derham, weather reporter Carol Kirkwood, and boxer Anthony Ogogo.