Robert played an important role in the succession of Philip VI of France (his wife's half-brother) to the throne, and was his trusted adviser for some time. However, since the death of his grandfather Robert II of Artois he had been involved in a succession dispute with his aunt Mahaut over the County of Artois. At her death in 1329, the claim passed to her daughter Jeanne II, Countess of Burgundy, and the matter of the succession was again raised. Robert introduced a forged letter in support of his claims on Artois, but was discovered. His goods were confiscated in 1331, and he fled the country in 1332 to escape arrest and execution, and took refuge with his nephew John II, Marquis of Namur. Philip confiscated his property, imprisoned his wife and his sons John and Charles, and requested that the Bishop of Liège attack Namur. Accordingly, Robert fled again to John III, Duke of Brabant, who had married his niece. Again, the influence of Philip stirred up a war against Brabant, and Robert was exiled again, this time to England.
Arriving in England in 1334, he encouraged King Edward III to claim the title of King of France as a descendant of Philip IV. He followed Edward in his campaigns thereafter, including command of the Anglo-Flemish army at the inconclusive battle of Saint-Omer in 1340; he ultimately succumbed to wounds incurred during the War of the Breton Succession. He is buried in St. Paul's Cathedral, in London.