Both agencies were picked after COI-managed pitches and have been tasked with raising awareness of the 2004 awards and driving nominations for 2005.
Geronimo pitched against Grayling, while the BME effort featured Focus Consultancy and Media Reach.
The annual awards are given to volunteer groups for outstanding achievement in community work.
The winners receive a certificate signed by the Queen and a crystal trophy at a ceremony.
Peter Gilheany heads the Geronimo team that will generate interest among the public, stakeholders and public bodies.
Media Moguls, led by Anjna Raheja, will focus on ethnic minority communities.
It is the first time that the COI has appointed agencies from its BME roster.