In Western astronomy, Monoceros is a relatively modern constellation, not one of Ptolemy's 48 in the Almagest. Its first certain appearance was on a globe created by the cartographer Petrus Plancius in 1612 or 1613 and it was later charted by German astronomer Jakob Bartsch as Unicornu on his star chart of 1624.

One of the nearest known black holes to the Solar System is in this constellation. The binary star system A0620-00 in the constellation of Monoceros is at a distance of roughly 3,300 light-years (1,000 parsecs) away. The black hole is estimated to be 6.6 solar masses.