The 2021 Grand Prix de Denain – Porte du Hainaut was the 62nd edition of the Grand Prix de Denain, a one-day road cycling race in and around Denain in northern France.

[4][5] This edition was the race's first in the UCI ProSeries; the 2020 edition was expected to feature in the inaugural UCI ProSeries but was cancelled due to the COVID-19 pandemic.

[6] It was also the eleventh event of the 2021 French Road Cycling Cup.

Additionally, the race was originally due to be held on 18 March but was postponed by COVID-19 precautions.

In total, 132 riders started the race, of which 86 finished.