The organisers of Kids Week have reported that the annual initiative has seen a record 85,336 tickets sold in the first 24 hours.
Revenue from paid tickets, which went on sale yesterday (17 June) at 10am, has already surpassed £2million.
Run by the Society of London Theatre (SOLT) since 1998, Kids Week lasts for the whole of August, with 37 shows offering free tickets to children.
A child aged 16 or under can go free to participating shows when accompanied by an adult paying full price. Up to two extra children's tickets can also be purchased at half price, per transaction.
Kids Week also offers a range of free activities giving young people, from under-fives to teenagers, the opportunity to explore backstage and the cast, crew and creatives behind some of the capital's biggest shows.
Julian Bird, chief executive of SOLT, said: "I am delighted Kids Week has achieved such robust figures in the first day of sales alone, with an incredible year-on-year growth. The London theatre industry really gets behind Kids Week to offer unrivalled opportunities for children to take centre stage every August, often giving them their first experience of the magic of live theatre."
There are still more than 50,000 tickets available for Kids Week shows, and allocations are topped up over the summer months.
The shows taking part in Kids Week 2014 are as follows:
Aliens Love Underpants, The Elephantom, The Tiger Who Came to Tea, What The Ladybird Heard
The 39 Steps, Charlie And The Chocolate Factory, Disney's The Lion King, Hetty Feather, Horrible Histories - Barmy Britain Part 2, I Believe In Unicorns, Let It Be, MAMMA MIA!, Matilda The Musical, Les Misérables, The Pajama Game, The Phantom Of The Opera, Stomp, Thriller Live, Top Hat, Wicked
Billy Elliot The Musical, The Bodyguard, The Commitments, The Curious Incident Of The Dog In The Night-Time, The Gershwin's Porgy And Bess, The Importance Of Being Earnest, Jeeves And Wooster In Perfect Nonsense, The Mousetrap, Shakespeare In Love, War Horse, The Woman In Black
Avenue Q, Ghost Stories, Jersey Boys, Let The Right One In, Once, A Small Family Business