ICMC is a commission of Catholic Bishops Conferences and Episcopal assemblies of similar status that work with migrants and refugees on national and regional levels. These conferences are referred to as ICMC Members.

ICMC is made up of a Council, Governing Committee and General Secretariat (headquarters). Council members are nominees of Catholic Bishops' Conferences and equivalent bodies working specifically with migration and refugee issues.

The 18-member Council elects the president of the commission, who convenes and chairs both the Council and Governing Committee meetings. Voting for the other members of the 11-member Governing Committee is regionally based. The Council is the policy-making organ of the Commission.

The Governing Committee carries out the decisions of the Council and supports their work, particularly in the preparation of annual budgets. Additionally, the Governing Committee appoints the Secretary General and prioritises and guides the work of the Secretariat.

The ICMC Secretariat is located in Geneva, Switzerland. This office is the executive organ of the Commission and is responsible for its daily activities. The Geneva headquarters serves as the Secretariat for all ICMC Members and as the central branch of ICMC policy work, further providing oversight and support to all ICMC field offices. Additional liaison offices are located in Brussels (ICMC Europe) and in Washington DC (ICMC Inc.).

ICMC is a registered non-profit organisation, governed by articles 60ff of the Swiss Civil Code. The organisation’s mandate is defined in its statues, recently updated and approved by ICMC Members and the Holy See in March 2007. In June 2008, the Vatican granted ICMC canonical public juridical status, testifying to the strengthened relationship between the Secretariat of State, the Bishops Conferences and the Commission.