Previous clues had told them that the area would be open at 0500.
Roberta Woodhouse, 29, Hannah Davies, 24, and Laura Hawkins, 22, broke out of the camera-filled mock prison in Cuffley, Hertfordshire, at 0516 BST.
Each woman will collect more than £30,000 for their successful getaway.
Ten contestants - five men and five women - entered the compound 14 days ago. They are drip-fed cryptic clues to help them find ways around the security measures.
Secret tunnels
Like Big Brother, the inmates have their every move tracked on the internet via 30 cameras, with edited highlights shown on television.
In the pre-planned break out, Woodhouse, Davies and Hawkins used a secret tunnel to get from their dormitory to the shower block.
Previous clues had told them that the area would be open at 0500.
They then made their way to a store room, through several number coded locks - which they had already cracked - and waded knee deep in water through a final tunnel to escape.
The three emerged outside the razor-wire ring-fenced compound and threw themselves on the Channel 5 Target which lit up, crowning them the winners of the show.
Solitary confinement
Hawkins screamed: "I can't believe it - we did it!" and the trio hugged each other and drenched themselves in champagne.
The remaining contestants can continue trying to find a way out although this time the prize will be £50,000 - again to be split between the escapees.
However, before the break out attempt, the five female contestants pledged to share the winnings if any one of them gained their freedom.
The other two women, Jenny Adams and Pat Chugg, were in solitary confinement as punishment for previous escape attempts when the trio got away.