Gallia Belgica (Belgic Gaul) was a province of the Roman empire located in Belgium, present-day northern France, Luxembourg, part of the present-day Netherlands below the Rhine, and the German Rhineland. It was originally composed of the lands of the alliance of the Belgae who had fought against Julius Caesar, plus the lands of their southeastern neighbours the Treveri, Mediomatrici and Leuci. The southern border of Belgica, formed by the Marne and Seine rivers, was reported by Caesar as the original cultural boundary between the Belgae and the Gauls who he distinguished as Celts.

Belgica was and is the name of two Belgian research vessels, with a name derived ultimately from the Latin Gallia Belgica.