The siege on a street in Cricklewood began shortly before midnight on Monday and ended at around 7am today when police stormed the property, officers said.
The police had originally attended the address to make arrest enquiries but said they spotted a man with a gun through a window.
Armed backup attended but the man refused to put down his weapon, barricading himself and a woman and two 14-year-old girls in the house, according to police.
A seven hour siege ensued as a specialist negotiator tried to talk the man into cooperating.
The residential street was cordoned off and all local roads were closed.
At around 6.50 on Tuesday morning armed officers stormed the property and ended the siege.
The woman, believed to be in her forties, and the two teenage girls were unharmed.
Local roads have now reopened.
Borough Commander for Brent Chief Superintendent Mick Gallagher said: "Officers acted professionally in what was a difficult situation that thankfully ended in a safe resolution with no one harmed.
"Police would like thank the local community for their co-operation throughout the operation."
A 31-year-old man was arrested for recall to prison and on suspicion of rape, threats to kill and possession of a firearm. He remains in custody at a north London police station.
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