DMC Healthcare has come under pressure in the last month over the level of care it is providing thousands of patients.
The south London-based company was last week stripped of contracts to run five GP surgeries in Medway.
This was after serious failings were found in an inspection by the Care Quality Commission (CCQ).
In June, it was suspended from operating three others in the Medway Towns and lost control of dermatology services across north and east Kent.
In a statement this morning, the firm said it had taken on previously "challenged" and "troubled" services from the NHS.
It is also walking away from its north Kent dermatology contract.
Kings Family Practice in Chatham - the only Medway surgery it wasn't suspended from running - is also being given back to the Kent and Medway Clinical Commissioning Group (CGG).
It is understood all the services combined have more than 50,000 patients on their books.
The statement said: "It is with deep regret the board is returning to the CCG the contracts for the delivery of primary care services.
"This decision has not been taken lightly and the reasons are complex.
"Experience shows turning around a failing practice can take up to three years dependent on size, premises, deprivation, staff culture and the clinical and contracting legacy.
"We appreciate the CCG and CQC recognised DMC has a successful track record of turning around practices and has worked hard to transform the quality of the service.
"We were afforded less than seven weeks to implement the dermatology service, what would normally need at least a year.
"It has also been noted the service we inherited had poor systems, virtually no data, was entirely paper based with a very significant undeclared backlog.
"The unplanned high demand from the backlog of patients proved challenging and meant that we in effect spent the year settling the service during which time we provided over 25,000 appointments.
"We are deeply sorry this has happened and the disruption to patient care and are working hard with the CQC and CCG to support service delivery.
The company has three other surgeries in Kent which aren't affected by this move.
Wilf Williams, accountable officer at NHS Kent and Medway Clinical Commissioning Group (CCG), said: “We are aware that DMC Healthcare has issued a statement explaining they are handing back contracts for both primary care and dermatology services.
"This is a complex process and although we are in negotiations with DMC, an agreement has not yet been reached.
“As always, our priority is to ensure continuity of care for our patients. We have put temporary providers in place for all the services affected and patients do not need to take any action.”
Visit www.kentandmedwayccg.nhs.uk/dmc for the latest information.