The doctor surgery in Gilfach will close at the beginning of next month.
Last year, Aneurin Bevan University Health Board (ABUHB) received an application from the Gelligaer Practice to close its Gilfach branch, which has since been backed by an independent panel.
ABUHB has said the branch will close on Friday, April 3.
Gilfach patients will now be transferred to the Gelligaer practice.
The announcement coincides with the closure of Lansbury Park and Troed y Bryn surgeries in Caerphilly being confirmed.
Caerphilly AM Hefin David described the closure as “very disappointing news for residents”.
He said: “We undertook a petition and made the strongest possible representations with Wayne David MP and local councillors to the health board.
“However, I will continue to work with the health board to ensure Gelligaer and Bryntirion surgeries get the support they need.
Dr David added: “I will also be pushing for extra use of the building at Bryntirion to accommodate and effectively deal with the intake of new patients. I will also be looking for the health board to fund extra appointments during the day at Bryntirion.
“Although the Gelligaer Practice faces the same pressures as any other surgery, the closure of Gilfach should not add to those pressures.”
Dr David called for “the same number of GPs serving the same number of patients at Gelligaer when Gilfach closes as before”.
Caerphilly MP Wayne David said: “I am extremely disappointed by the decisions. Unfortunately, the health service in our area and in Wales is buckling under the pressure of the crisis which is affecting the health service throughout the UK.
“At the end of the day, the UK Government has to increase funding to Wales so that issues of GP recruitment are addressed.
“The question of funding has to be addressed and I am fighting for more funding as strongly as I can.”
South Wales East AM Delyth Jewell said: “Patients in Gilfach will be understandably distressed at the news that their local branch is closing, despite an energetic campaign to keep it open.
“Whilst it’s understandable that the practice would wish to merge back-office functions to Gelligaer to save money, it’s extremely disappointing that they’ve decided to close the Gilfach branch.
“I’ll be writing to the health board to ask for assurances that the increased demand on these surgeries will be met by increased provision, so that patients can continue to be able to see their GP in a timely manner.”
A spokesman for Aneurin Bevan University Health Board said: “Patients will continue to access their general medical services from the main site in Gelligaer after this time.
“Patients do not need to do anything as they will remain registered with Meddygfa Gelligaer. Alternatively, patients can choose to register with an alternative neighbouring practice if they wish to do so, providing they live within the boundary of that practice.”
The spokesman added: “Patients will receive a letter containing information regarding the future of their care, and they will be given the opportunity to attend a number of drop-in sessions to ask questions or discuss any concerns they may have.
“We will continue to keep patients and their local elected representatives fully informed as these changes progress.”