The wedge-tailed shearwater was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae.

[2] Gmelin based his description on the "Pacific petrel" that had been described in 1785 by the English ornithologist John Latham in his book A General Synopsis of Birds.

This species is related to the pan-Pacific Buller's shearwater, which differs much in colour pattern, but also has a wedge tail and a thin, black bill.

[10][11] They make up the Thyellodroma group, a superspecies of the large shearwaters that were for a long time included in the genus Puffinus.

The species was thought to mostly take food from surface feeding, but observations of feeding wedge-tails suggested that contact-dipping, where birds flying close to the surface snatch prey from the water was the most commonly used hunting technique.

The breeding season of the Bonin petrel in Hawaii is timed to avoid that of the wedge-tail; in years where Bonin petrel chicks are still in burrows when wedge-tails return to begin breeding, these chicks are killed or evicted.

It attends these colonies nocturnally, although nonbreeding wedge-tails are often seen at the surface throughout the day and breeding birds rest outside their burrows before laying.

Both sexes undertake a prelaying exodus to build up energy reserves; this usually lasts around 28 days.

After hatching, the chick is brooded for up to 6 days, until it is able to thermoregulate, after which it is left alone in the nest while both parents hunt for food.