The arrondissement of Riom is an arrondissement of France in the Puy-de-Dôme department in the Auvergne-Rhône-Alpes region.

[2] Its population is 137,149 (2021), and its area is 2,705.3 km2 (1,044.5 sq mi).

[3] The communes of the arrondissement of Riom, and their INSEE codes, are:[2] The arrondissement of Riom was created in 1800.

[5] As a result of the reorganisation of the cantons of France which came into effect in 2015, the borders of the cantons are no longer related to the borders of the arrondissements.

The cantons of the arrondissement of Riom were, as of January 2015:[6]