Its name is Latin for "the southern triangle", which distinguishes it from Triangulum in the northern sky and is derived from the acute, almost equilateral pattern of its three brightest stars.

It was first depicted on a celestial globe as Triangulus Antarcticus by Petrus Plancius in 1589, and later with more accuracy and its current name by Johann Bayer in his 1603 Uranometria.

The French explorer and astronomer Nicolas Louis de Lacaille charted and gave the brighter stars their Bayer designations in 1756.

The Great Attractor, the gravitational center of the Laniakea Supercluster which includes the Milky Way galaxy, straddles between Triangulum Australe and the neighboring constellation Norma.

He learnt to recognize the stars in the southern hemisphere and made a catalogue for his patron king Manuel I of Portugal, which is now lost.

[3] The first depiction of the constellation was provided in 1589 by Flemish astronomer and clergyman Petrus Plancius on a 32+1⁄2-cm diameter celestial globe published in Amsterdam by Dutch cartographer Jacob van Langren,[4] where it was called Triangulus Antarcticus and incorrectly portrayed to the south of Argo Navis.

His student Petrus Keyzer, along with Dutch explorer Frederick de Houtman, coined the name Den Zuyden Trianghel.

[5] Triangulum Australe was more accurately depicted in Johann Bayer's celestial atlas Uranometria in 1603, where it was also given its current name.

[8] The Wardaman people of the Northern Territory in Australia perceived the stars of Triangulum Australe as the tail of the Rainbow Serpent, which stretched out from near Crux across to Scorpius.

[9] Triangulum Australe is a small constellation bordered by Norma to the north, Circinus to the west, Apus to the south and Ara to the east.

[12] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 18 segments.

The brighter star, Epsilon Trianguli Australis A, is an orange K-type sub-giant of spectral type K1.5III with an apparent magnitude of +4.11.

[22] The optical companion, Epsilon Trianguli Australis B (or HD 138510), is a white main sequence star of spectral type A9IV/V which has an apparent magnitude of +9.32.

[23] Zeta Trianguli Australis appears as a star of apparent magnitude +4.91 and spectral class F9V, but is actually a spectroscopic binary with a near companion, probably a red dwarf.

[29] Of apparent magnitude 5.11, the yellow bright giant Kappa Trianguli Australis of spectral type G5IIa lies around 1,207 light-years (370 parsecs) distant from the Solar System.

Despite their faintness, Benjamin Gould upheld their Bayer designation as they were closer than 25 degrees to the south celestial pole.