The name was first recorded in 1225 in Västergötland, Sweden, in the Latin form Gostauus.

[1] Linguistic Otto von Friesen suggested that it may derive from a byname meaning "staff of the Göta people" or "support of the (Väst)göta people".

Another theory speculates that the name is of Medieval Slavic origin, from Gostislav,[2] a compound word meaning "glorious guest", derived from the Slavic words ghosti ("guest") and slava ("glory"), and was adopted by migrating groups north and west into Germany and Scandinavia.

In French it is Gustave; in Italian, Portuguese, and Spanish it is Gustavo.

The name in Finnish is Kustaa, while in Icelandic it is written Gústav or Gústaf.