Police discovered 16 people living in a two-bedroom flat in a dawn raid in Brent.
Officers entered the property in Kingsbury, north west London, found three times the number of people who would be permitted to live there under licensing rules.
Mattresses, bunkbeds and sofa beds had been packed together in the two bedrooms and living room space within the poorly ventilated flat.
Fire escapes had been blocked while a smoke alarm was found hanging off the ceiling during the raid on May 24.
One occupant told enforcement officers that he was paying £50 a week for a bed space.
If each of the 16 tenants paid the same amount, the landlord may have been pocketing around £3,200 a month from housing the occupants in substandard living conditions.
Cllr Eleanor Southwood, cabinet member for Housing and Welfare Reform, said: "Housing tenants in unsafe conditions is against the law.
"Housing tenants in unsafe conditions is against the law. Rogue landlords exploiting their tenants by forcing them to live in Dickensian conditions should be on notice.
"We will take the strongest possible enforcement action to protect our residents."
Additional reporting by the Press Association
