It's the Catholic Church's latest move to help disadvantaged people after it opened a shower facility last year.
The 'Clinic for the Poor' will provide free medical treatment to those who cannot afford basic care.
Archbishop Konrad Krajewski told Vatican Radio: "We are equipped to help all those who come knocking on our door. It is Pope Francis who wants this and those of us who are close to him in this venture are honoured and highly motivated to make this possible."
The Church said the centre was a "concrete sign of mercy in St. Peter's Square" and would be staffed by experienced doctors from a nearby hospital.
"It is an indispensable service to the health of the poor who live among us," Archbishop Konrad added.
