With more than 1900 participants from 141 Member States, four non-Member States and 25 international organizations, the International Conference on Nuclear Security (ICONS 2020) was convened to formulate and exchange views on experiences and achievements, current approaches, future directions and priorities for nuclear security. An outcome of ICONS 2020 was Member States adopting by consensus, a ministerial declaration reaffirming their support for nuclear security. This publication includes the co-presidents' summary of the conference, the full text of the ministerial declaration, statements from the opening and closing sessions, and an outline of the conference programme. The supplemental files presented with this publication contain the full conference programme, the list of conference participants, the national statements from the ministerial segment, and a selection of papers and presentations.