The contract covers all CIPS' departments and has been awarded for two years, with the option to extend for an additional two years.
Conference Care passed a request for proposal (RFP) selection process to become the sole supplier.
CIPS head of event management Sara Strid-Coughlan said: "We believe Conference Care's strong customer-service level, vast venue knowledge, sophisticated online management reporting systems, as well as its robust sustainability programme will add tremendous value for us and our members."
Conference Care director Chris Peacock said: "We are absolutely delighted to be aligned with such a prestigious industry body. This is an outstanding account win for Conference Care, endorsing our reputation for unrivalled service excellence and customer-focused ethos."