The agency has promised to "abide by the PRCA code of ethical conduct on a voluntary basis".
The UK PR trade body's professional practices committee (PPC) concluded that the agency had breached both its professional charter and its public affairs and lobbying code of conduct, in its work for Oakbay Investment, a South African conglomerate whose owning family has close links to the country's president.
The PRCA's board unanimously agreed with the PPC's recommendation that Bell Pottinger's membership be revoked, and earlier today rejected an appeal made by the agency against the committee's decision.
It was concluded by the PPC that the agency had run a campaign that "was by any reasonable standard of judgement likely to inflame racial discord in South Africa", had itself admitted that aspects of its work "should never have been undertaken" and that it had in turn caused "damage to the reputations of both Bell Pottinger and the profession of public affairs and lobbying".
Today, Bell Pottinger CEO James Henderson announced his resignation from the firm over its work for Oakbay, as an independent law firm's report into the company confirmed that it had run an "unethical" campaign that was liable to cause offence and racial division.
A Bell Pottinger statement said it "disputed" the basis on which the decision was made, but acknowledged there were "lessons to be learned", and said: "In common with those of our major competitors who are not corporate members of the PRCA, we will abide by the PRCA code of ethical conduct on a voluntary basis.
"The overwhelming majority of our partners and employees played no part in the Oakbay Capital account and have not been accused of breaching the PRCA code. Many of them will now consider applying for individual membership. With the Herbert Smith Freehills findings made publicly available and the PRCA ruling published, the business can refocus on delivering outstanding work for our clients and looking after our people."
Bell Pottinger joined the PRCA in 2013. It paid around £15,000 last year to be a member, or around one per cent of the body's total membership subscriptions.
Neither Bell Pottinger, nor any future company formed out of it, will not be allowed to apply for PRCA membership for five years, although individual membership is an option.
Lord Bell, its co-founder, will remain a PRCA fellow. Bell is no longer a shareholder in the agency, and has maintained that he was not involved in the work before leaving the firm in August last year.
PRCA director general Francis Ingham said: "Bell Pottinger has brought the PR and communications industry into disrepute with its actions, and it has received the harshest possible sanctions. The PRCA has never before passed down such a damning indictment of an agency’s behaviour.
"This outcome reflects the huge importance that the PRCA places on the protection of ethical standards in the business of PR and communications."
The only other agency expelled from the PRCA in Ingham's ten-year tenure was Fuel PR, after it provided a case study under false pretences to the media.
Ingham told PRWeek that it would be "very welcome" if the Bell Pottinger case increased the level of scrutiny on the industry, adding: "In doing the right thing, and taking decisive action, we have proved that the PRCA is willing and able to uphold ethical standards in the PR and communications industry."
In a nod to the APPC and CIPR, which have both suggested they would look into the matter but have not made public any such outcome, Ingham said: "There are three types of practitioner – those who are unregulated; those who are regulated by associations that take no action; [and] those who are PRCA members."