Grand-Popo is a town, arrondissement, and commune in the Mono Department of south-western Benin. The commune covers an area of 289 square kilometres and as at the 2013 Census had a population of 57,636 people.

Mono is one of the twelve departments of Benin, with its capital at Lokossa. It is named for the Mono River which forms much of the border with Togo. The northern areas of the department were split off to create the newly formed Kouffo Department in 1999. Mono is subdivided into six communes, each centred at one of the principal towns, namely, Athiémè, Bopa, Comè, Grand-Popo, Houéyogbé and Lokossa. It has an area of 1,396 square kilometres (539 sq mi).