Arnould III, Count of Guînes (c. 1222–1283) was a French nobleman.

Arnould was the eldest son of Baldwin III, Count of Guînes and Mahaut de Fiennes.

Louis IX of France meditated his release, with an agreement that Arnould will remove the tolls he had installed.

Captured during the battle of Westkapelle on 4 July 1253, Arnould was forced to pay a large ransom for his release.

He was forced to sell his castle of Montoire to the Count of Artois in May 1281 and then the County of Guînes to Philip III of France in February 1283 for 3,000 livres and a life annuity of 1,000 livres.