An apostolic vicariate is a territorial jurisdiction of the Catholic Church under a titular bishop centered in missionary regions and countries where dioceses or parishes have not yet been established. It is essentially provisional, though it may last for a century or more. The hope is that the region will generate sufficient numbers of Catholics for the Church to create a diocese. In turn, the status of apostolic vicariate is often a promotion for a former apostolic prefecture, while either may have started out as a mission sui iuris.

It is exempt, directly subject to the missionary Congregation for the Evangelization of Peoples of the Vatican in Rome. Like the stage of apostolic prefecture which often precedes it, the vicariate is not part of an ecclesiastical province. It is intended to mature in developing Catholic members until it can be promoted to a (usually suffragan) diocese.

The Eastern Catholic counterpart is an (apostolic, patriarchal, or archiepiscopal) exarchate.