Aims. During the last ~50 years, the population of black hole candidates in X-ray binaries has increased considerably, with 59 Galactic objects being detected in transient low-mass X-ray binaries, as well as a few in persistent systems (including ~5 extragalactic binaries). Methods. We collect near-infrared, optical, and X-ray information spread over hundreds of references to study the population of black holes in X-ray transients as a whole. Results. We present the most updated catalogue of black hole transients. This contains X-ray, optical, and near-infrared observations, together with their astrometric and dynamical properties. The catalogue provides new and useful information in both statistical and observational parameters and provides a thorough and complete overview of the black hole population in the Milky Way. Analysing the distances and spatial distribution of the observed systems, we estimate a total population of ~1300 Galactic black hole transients. This means that we have only discovered less than ~5% of the total Galactic distribution.