The local council in Hackney, east London, took legal action against four landlords for breaching conditions of the new HMO licences.
The town hall brought in a policy in October that requires HMO owners in the borough to get a licence.
There are approximately 4,000 HMOs in the borough that require a licence, according to Hackney Council.
The HMO licensing scheme introduced recently is part of the Better Renting campaign that targets unscrupulous landlords, and some of the serious cases have now led to legal action.
Also, there was introduces a selective licensing scheme for landlords renting out any property in what has been identified as the most problematic areas locally, including, Brownswood, Cazenove and Stoke Newington wards.
The mayoral advisor for private renting and housing affordability, Cllr Sem Moema, said: “Property licensing is a key part of our crackdown on rogue landlords, and means renters who are most likely to experience hazards and poor treatment can finally get the protection they deserve.”