The girls, Cleo Demetriou, Kerry Ingram, Sophia Kiely and Eleanor Worthington-Cox, were named joint winners of the Best Actress in a Musical award.
One of the girls - 10-year-old Eleanor made history becoming the youngest ever winner of an Olivier.
She said her win was “pretty cool” and said her last prize was a “little silver plastic medal” for athletics at school.
Kerry said she was “mind-blown” by the success and Cleo said winning the award was “a million times bigger” than the audience reaction at the end of each show.
The show, based on the Roald Dahl book, won seven awards including Best New Musical and Best Actor in a Musical for Bertie Carvel.
Carvel paid tribute to his young co-stars, saying: “There is something beautifully unfinished about them and full of life”.
He added: “I’m proud of my part in it but frankly I’m proud of every inch of it, it’s really witty, inventive, it’s the kind of theatre I want to go and see which is the kind of theatre I want to be in”.
The ceremony switched to New York via a live link when Best Director winner Matthew Warchus picked up his award from James Earl Jones for his work on Matilda.
He paid tribute to his young leading ladies, saying: “People often say to me ‘Matthew, which is your favourite Matilda?’ and as you saw earlier it’s a ridiculous question, there are four little miracles there”.
Earlier in the night, stars including Ronan Keating, Sir Tim Rice and Dan Stevens met fans and posed for photographs on the red carpet.
The bash - the biggest night in theatreland - also attracted names including Girls Aloud star Kimberley Walsh and Kara Tointon to the ceremony at the Royal Opera House in Covent Garden, central London.
The event, properly known as the 2012 Olivier awards with Mastercard, was hosted by Michael Ball and Imelda Staunton and shown on a big screen in Covent Garden, London.
It kicked off with a performance of Queen’s Bohemian Rhapsody from the cast of the musical We Will Rock You featuring the band’s guitarist Brian May.
The first big winner was Sheridan Smith who was recognised for Best Performance in a Supporting Role for her performance in Flare Path.
Her award was picked up for her by Sir Trevor Nunn who read a message from the actress who is filming in Australia.
In her message, she said: “This is one of the most special jobs I have ever done and I feel honoured to be have been part of such a brilliant revival”.
She also paid tribute to her parents who were in the audience and the members of RAF Bomber Command whose lives inspired the Terence Rattigan play.
Also getting gongs were Luther-star Ruth Wilson who was named Best Actress and Jonny Lee Miller and Benedict Cumberbatch who shared the Best Actor gong for their role in Frankenstein.
Accepting the award for both of them, Lee Miller paid tribute to the National Theatre which staged the show.
He said: “It’s an amazing place and I can’t say enough about it, thank you to Nicholas Hytner and the entire staff of the National. It’s a magical place and I can’t wait to get back”.
Speaking backstage, he hinted that the show, directed by Danny Boyle, could reappear at another venue - saying “there is talk, some talk” but added it would “seem like a huge mountain to climb” to stage it anywhere but the National.
Long-running musical Les Miserables won the Radio 2 Olivier Audience Award voted for by the general public.
Sir Tim Rice was given an Olivier Special award and the National Theatre’s Collaborators was awarded MasterCard Best New Play Award.
New Play: “Collaborators”
New Musical: “Matilda The Musical”
Entertainment: “Derren Brown - Svengali”
Revival: “Anna Christie”
Musical Revival: “Crazy For You”
Actress-Play: Ruth Wilson, “Anna Christie”
Actor-Play: Benedict Cumberbatch and Jonny Lee Miller, “Frankenstein”
Actress-Musical: Cleo Demetriou, Kerry Ingram, Sophia Kiely and Eleanor Worthington-Cox, “Matilda The Musical”
Actor-Musical: Bertie Carvel, “Matilda The Musical”
Supporting Performer-Play: Sheridan Smith, “Flare Path”
Supporting Performer-Musical: Nigel Harman, “Shrek”
Director: Matthew Warchus, “Matilda The Musical”
Theater Choreography: Peter Darling, “Matilda The Musical”
New Opera Production: “Castor and Pollux,” English National Opera
Outstanding Achievement in Opera: English National Opera
New Dance Production: “Desh,” Akram Khan Company
Outstanding Achievement in Dance: Edward Watson, “The Metamorphosis”
Set Design: Rob Howell, “Matilda The Musical”
Lighting Design: Bruno Poet, “Frankenstein”
Sound Design: Simon Baker, “Matilda The Musical”
Costume Design: Peter McKintosh, “Crazy For You”
Audience Award for Most Popular Show: “Les Miserables”
Outstanding Achievement in an Affiliate Theater: “Roadkill,” Theatre Royal Stratford East/Barbican/Traverse Theatre
Special Awards: Monica Mason, Tim Rice