Patrick Clarke said he was standing down from Newry Mourne and Down District Council on medical grounds.
In the past two years, the councillor, from Castlewellan, had been convicted of sexually assaulting a woman at a hotel in Newcastle.
He was convicted of two further charges of defrauding community groups.
He also forced his way into a neighbour's house armed with a hammer.
Last month, he became the first councillor in Northern Ireland to be the subject of an adjudication hearing by the Local Government Commissioner for Standards.
He admitted breaching the councillors' code of conduct and could face a range of possible sanctions including disqualification as a councillor for up to five years.
The hearing was  adjourned to next week for a decision on what punishment the Independent councillor may face.
But he is now submitting his resignation saying he was suffering from depression and "alcohol issues" adding he has now accepted he has to address his problems.
Mr Clarke, who was elected as an Alliance councillor but later resigned from the party, apologised to his family, friends and the electorate.
A councillor with convictions for sexual assault and fraud has quit politics after admitting breaching the local government code of conduct.