A dawn raid in Wembley found 19 people including two children living in a four bedroom semi-detached house.
The raid on the premises in Nathan Road, Wembley was a joint operation between Brent council, police and the UK Border Agency.
According to Brent Council, the tenants at the property on Nathans Road in Wembley included two children.
The 19 tenants paid the landlord £1,000 a week.
Brent Council’s licencing team found that a garage had been illegally turned into two bedrooms with a makeshift partition wall between them.
Images and video footage from the premises show the conditions in which the tenants were living in.
The back garden can be seen covered in rubbish while the rooms are cramped.
Building works on a shed were also seen in the video.
Councillor Eleanor Southwood, cabinet member for housing and welfare reform, said: “A landlord making £4,000 a month from exploiting tenants like this is committing an offence.
“We won’t hesitate in taking action against people who continue to treat tenants badly and provide homes that are unsafe.
"Our licensing scheme is clear. It requires landlords to meet certain standards and a landlord or agent who rents out to tenants without a licence is breaking the law.”
