16 January – Ministry of the Environment and Spatial Planning of the Republic of Slovenia grants a 20-year extension for operation of the Krško Nuclear Power Plant.[2]
25 June – Slovenia and Israel host the EuroBasket Women 2023 tournament, with Slovenian team not progressing beyond the group stage.[6]
6 August – 2023 Slovenia floods: a protracted period of heavy rain leads to flooding in large parts of northern, central and eastern Slovenia, necessitating evacuation of thousands of people, and causing at least six casualties and billions of euros of structural damage (according to early estimates), the worst natural disaster in modern history of the country.[7]
19 December – Slovenian Armed Forces receive the first of the two military transport aircraft Alenia C-27J Spartan ordered as part of the agreement on military cooperation between Italy and Slovenia.[8]
Deaths
1 January – Mako Sajko, documentarist, screenwriter and film director (born 1927).[9][10]
3 February - Bine Rogelj, ski jumper and caricaturist (born 1929).[11]
6 May – Ivan Bizjak, mathematician and politician (born 1956).[12]