The Plenary Assembly is one of the constituent bodies of the CoR, bringing together all the members of the Committee. It is convened by the President of the Committee, and nowadays, the CoR holds up to 6 plenary sessions each year.

The Plenary sessions, chaired by the CoR's President, give the opportunity for CoR Members (or Alternates) to voice their opinions on EU laws that may have an impact on regions and cities in the EU Member States.

The main purpose of the plenary sessions is: to vote on opinions, reports and resolutions, to adopt the CoR's political programme at the beginning of each term, to elect a President, first Vice-president and the remaining members of the Bureau, to set up policy commissions within the institution, to approve the CoR's draft estimates for expenditure and revenue and to revise and agree on the CoR's Rules of Procedure.