Officers forced entry to the house in Wood End Lane, Northolt, west London, at about 20:10 BST and detained a man in his 40s.
They say a search of the house is under way to make sure it is safe so that evacuated neighbours can return home.
Police said negotiations with the man had been unsuccessful.
A cordon of 200m had been in place at Wood End Lane since 01:00 BST on Friday, which was extended to 300m on Saturday.
About 80 residents have had to spend two nights away from their homes as officers negotiated with the man.
Scotland Yard said officers from the Territorial Support Group were supported by the London Fire Brigade as they moved in on the address.
Ch Supt Paul Martin said: "I am really pleased that this incident has now ended, and importantly ended without anyone coming to harm.
"Our key priority throughout this was to get the man out of the address safely as we had growing concerns about his well-being and believed him to be in crisis.
"After attempts to negotiate over a number of days did not work we used specialist officers to work out how we could gain entry to the address as safely as we could. They did that this evening."
Ch Supt Martin said police had also worked closely with the ambulance service and the local authority during the operation.
Searches of the property will be conducted "as quickly as we can to make sure people get home", he added.
Police had said there was no suggestion the incident was terror-related or linked to any ongoing police operations or investigation.
A three-day stand-off between armed police and a man feared to have stockpiled petrol at his home has ended after officers entered the property.