  Context: One of the rarest types of variability is the phenomenon of
gravitational microlensing, a transient brightening of a background star due to
an intervening lensing object. Microlensing is a powerful tool in studying the
invisible or otherwise undetectable populations in the Milky Way, including
planets and black holes. Aims: We describe the first Gaia catalogue of
microlensing event candidates, give an overview of its content and discuss its
validation. Methods: The catalogue of Gaia microlensing events is composed by
analysing the light curves of around 2 billion sources of Gaia Data Release 3
from all over the sky covering 34 months between 2014 and 2017. Results: We
present 363 Gaia microlensing events and discuss their properties. Ninety
events were never reported before and were not discovered by other surveys. The
contamination of the catalogue is assessed to 0.6-1.7%.
