“De Selby (Part 2)” is the third and final single and the sequel to the opening track on Hozier’s third studio album, Unreal Unearth. The track takes inspiration from De Selby, an eccentric fictional philosopher, and scientist featured in Flann O'Brien’s novel The Third Policeman. The lyrics explore darkness in the context of connection; to self, to other, and to a sense of time and space. According to Hozier in a letter to his fans, he stated that “De Selby Part 2” took its place in the opening of the album together with its prequel and seemed as a fitting addition to advance into the Circles of Hell that follow, while also mentioning the tracks together are some of his favorites in the album.

The track made its debut during a live performance in Gardone Riviera, Italy at Anfiteatro del Vittoriale. It was first teased on June 28, 2023, via autographed postcards Hozier sent to fans who had pre-ordered the album, revealing “De Selby (Part 2)” was track 2 on the album together with a snippet of the lyrics. The track was then used to reveal Unreal Unearth’s tracklist and was officially announced for release on July 22, 2023.