The CTO has two broad categories of members: Countries, and ICT Sector Members.  Full Member Countries are member states of the Commonwealth that have given an undertaking to make an annual payment to the CTO; Member countries are all other member states of the Commonwealth.  ICT Sector Members pay an annual membership fee and include other government departments or regulators, private sector companies, civil society organisation, international organisations, and other entities that share the CTO’s objectives.  Non-Commonwealth countries are welcome to join the CTO as ICT Sector Members.

The CTO also has a Programme for Development and Training that has separate membership, and is designed primarily to enable members to participate in each other’s capacity development and training schemes.