At which 2019 event was Diablo IV first officially announced?

Diablo IV was first officially announced at BlizzCon 2019.

Blizzard Entertainment revealed Diablo IV during BlizzCon 2019, its annual fan convention. The announcement included a cinematic trailer and gameplay footage, confirming that the series would return to a darker, more gothic visual style after Diablo III.

The reveal introduced Lilith as a central figure in the game’s story and showed a world shaped by demonic conflict. Blizzard also emphasized open-world exploration, shared-world elements, mounted travel, and a return to more grounded horror imagery. These details distinguished the project from the brighter presentation associated with parts of Diablo III.

The announcement is sometimes confused with BlizzCon 2018, where Blizzard revealed Diablo Immortal. That mobile game announcement received a notably different audience reaction, but it was not the reveal of Diablo IV. Diablo IV was later released in 2023 for Windows, PlayStation 4, PlayStation 5, Xbox One, and Xbox Series X/S.