The bird is 38–41 cm length, with a 97 cm wingspan, and weighs about 360 g.[2][3] Its plumage is all dark sooty-grey, except for a pale chin, and pinkish legs;[2] it does not exhibit sexual dimorphism.

[4] It was described by Robert Cushman Murphy in 1949, which is the source of the species' common name.

Murphy's petrels take unusually long feeding trips during incubation.

It occurs in the South Pacific, nesting on rocky islets and cliffs off tropical oceanic islands in the Austral, Tuamotu, and Pitcairn groups.

[1] It was not until the 1980s that it was determined that these petrels might be regular visitors far offshore of the west coast of North America.