- January 1- Millennium celebrations take place throughout the world. Y2K passes without the serious, widespread computer failures and malfunctions that had been predicted.
- January 1- Unification of Szeged's universities, called University of Szeged.
- January 5-January 8 – The 2000 al-Qaida Summit
- January 10 – America On-line announces an agreement to buy Time Warner for $162 billion. This is the largest-ever corporate merger.
- January 11 – The trawler Solway Harvester sinks off the Isle of Man.
- January 14 – A United Nations tribunal sentences five Bosnian Croats up to 25 years for the 1993 killing of over 100 Muslims in a Bosnian village.
- January 16 – In Sacramento, California a commercial truck carrying evaporated milk is driven into the state capitol building killing the driver.
- January 31 – Dr Harold Shipman is sentenced to life in prison for murder of at least 15 of his patients out of 365 suspected victims.