Mariah trained at the Guildhall School of Music and Drama, where she earned a first class BA in Acting. She is also an Associate Artist at the Royal Shakespeare Company, where she has recently finished playing Margaret in Henry VI: Rebellion, Wars of the Roses and Richard III.

Her roles at the RSC have included Juliet, Ophelia, Miranda, Portia in Julius Caesar, Celia, The Princess of France, Elaine of Astolat in Morte D’Arthur and Wendy Darling in Wendy and Peter Pan. She has performed Shakespeare for Her Majesty the Queen and Prince Charles and performed for the RSCs televised ‘Shakespeare Live!’ event.

Other theatre credits include A Midsummer Night’s Dream, Much Ado About Nothing and Measure for Measure (Shakespeare’s Globe); Twelfth Night (Regent’s Park Open Air Theatre); Three Sisters (Young Vic); Waiting For Lefty (Two Lines Productions); Afterplay (The Coronet); Eden (Hampstead Theatre); Cat on a Hot Tin Roof at The Manchester Royal Exchange, Catherine in Proof at the Menier Chocolate Factory, Kayleen in Gruesome Playground Injuries at The Gate, Hayley in Pitchfork Disney and Klara in Musik at The Arcola, Rose in The Sea at Theatre Royal Haymarket, Ella/Taylor in Vernon God Little at the Young Vic, Anabella in ’Tis Pity She’s A Whore at the Southwark Playhouse, Rowan in The Lost Child at Chichester festival Theatre and Emily in Stealing Sweets and Punching People at The Latchmere.

She was awarded the Laurence Olivier bursary whilst training at Guildhall, and throughout her career has been awarded the Ian Charleson Award (First Prize and Special Commendation), a Time Out Live Award, a Critics Choice Award, a Best Actress Evening Standard award nomination, and two Best Supporting Actor nominations at the OFFIE Awards.

Screen credits include I May Destroy You, Broadchurch, Dr Who, The Great, Death Comes To Pemberley, New Tricks, Grantchester, Father Brown, Lucky Man, The Hollow Crown, Skins, The Diary Of Anne Frank, Oliver Twist, Hamlet, Rare Beasts, Abraham’s Point and Hercules 3D. Extensive radio work includes Brian Guillivers Travels, seasons I and II.