The 75th anniversary of the United Nations is an apt moment to reflect on the current status and envisage potential bold reforms to the architecture of the UN system. While political barriers to change are hard to overcome, imagining transformations can spur discussion in helpful ways and identify areas where fresh attention is needed. This paper argues that the UN Security Council’s ineffectiveness in addressing arising complex security challenges, such as conflict re-escalation, climate change and COVID-19, among others, can be solved by establishing three additional Councils: a Peacebuilding Council, a Climate Security Council, and a Health Security Council. Each would focus on a specific security-related agenda, operate openly, transparently, responsibly, and without veto. The current Security Council remains the primary organ focusing entirely on Chapter VII actions in response to threats to international peace and security. The three new Councils do not undermine all privileges of the current permanent members of the Security Council, but benefit from larger, more representative configurations of Member States, amplifying their voice for world peace, which in turn brings new ideas, expertise, funds, services, and capacities to strengthen international peace and security, and engages relevant UN agencies, other organizations, and actors to ensure well-informed decisions. This innovative model aims to contribute to the debates leading up to and following the UN75, to be taken up by governments committed to multilateralism, major regional organizations, and the UN Secretary-General in the coming years. An independent expert commission should be established to study and elaborate on this proposal further.