Its distribution overlaps broadly with the similar northern giant petrel, though it overall is centered slightly further south.

Adults of the two species can be distinguished by the colour of their bill-tip: greenish in the southern and reddish in the northern.

The southern giant petrel was formally described in 1789 by the German naturalist Johann Friedrich Gmelin.

[2] Gmelin cited the "giant petrel" that had been described and illustrated in 1785 by the English ornithologist John Latham in his A General Synopsis of Birds.

Due to the large amount of size variability, it is difficult to determine which is the larger species, but the largest-bodied colonies of the southern species are slightly larger on average, in both mass and linear dimensions, than the largest in the northern giant petrel.

On the dark morph the upper breast, head and neck are light with the remainder of its plumage being mottled brown.

This can be sprayed out of their mouths as a defence against predators and used as an energy rich food source for chicks and for the adults during their long flights.

[20][9] Its nest is a mound of moss, grass, and stones with a depression in the centre and is located on bare or grassy ground.

The official generation trend listed by BirdLife International is a 1%–9% decline, but it is stated that this is a conservative number.

Additionally, the number of southern elephant seals, which is an important source of carrion, has been diminishing.

[13] To assist in the southern giant petrel's continued survival, it was listed in CMS Appendix II and ACAP Annex I.

[13] Continued monitoring and surveys at major breeding sites have been proposed, as well as researching movement and migration.

Additionally, continued promotion of "best-practice mitigation measures" via existing methods outlined in CCAMLR, CMS, and FAO have also been proposed.