Democratic Party (PD) member Marino, 60, has signed a letter "by which he withdraws his resignation presented on October 12," the local authority said in a statement.
He was quick to share the news with his followers on Twitter.
A vote of no confidence in Rome's 48-member municipal council could still force the former surgeon from Rome's top job.
PD president Matteo Orfini on Thursday called a meeting of the party's 19 city councillors, with Italian media reporting that they had agreed to collectively resign if Marino stays in his post.
The Democratic Party councillors would need support from another six fellow councillors to force Marino out, but it seems unlikely that he could command a majority in the 48-seat chamber.
Marino's deputy mayor Marco Causi, along with several other senior municipal officials, have themselves resigned.
Marino, one of the most unpopular politicians in Italy, has been under fire for months, facing mounting public anger over litter-strewn and pot-holed streets, a failing public transport system and revelations of mafia infiltration of the municipal authority.
These are all problems which predate his arrival in office in 2013, but most recently the embattled mayor has faced media scrutiny over restaurant bills settled with a city hall credit card, in a case dubbed "Dinnergate".
He said all the money had been spent legitimately on official entertainment but that he would cover the cost as a personal gift to the cash-strapped capital.
Marino was elected with a strong reputation for personal honesty, but his administration has been buffeted by a series of damaging stories since he began his five-year term in 2013.
These range from the revelation that he drove his Fiat Panda in traffic-restricted areas with an expired permit to stories that regularly suggest Prime Minister Matteo Renzi regards his party colleague as a liability.
Police last year dismantled the "Mafia Capitale" network, with dozens of local politicians and businessmen, suspected of rigging tenders and siphoning off millions of euros destined for public services, due to go on trial next month.
Marino was unscathed by the scandal but his critics say he is simply not up to the job, with some pointing out that "Dinnergate" was not the first expenses scandal to engulf him.
In 2002, Marino resigned as director of a transplant centre in Sicily after being accused of submitting the same expenses claim to both the centre and its US partner, the University of Pittsburgh Medical Center.