Robert I (c. 865 - June 15, 923), king of Western Francia, or king of the Franks, was the younger son of Robert the Strong, count of Anjou, and the brother of Odo, or Eudes, who became king of the western Franks in 888.

He was present at the Siege of Paris in 885. Appointed by Odo ruler of several counties, including the county of Paris, and abbot in commendam of many abbeys, Robert also secured the office of duke of the Franks, a military dignity of high importance. He did not claim the crown of Western Francia when his brother died in 898; but recognizing the supremacy of the Carolingian king, Charles III, the Simple, he was confirmed in his offices and possessions, after which he continued to defend northern Francia from the attacks of the Normans.

The peace between the king and his powerful vassal was not seriously disturbed until about 921. The rule of Charles, and especially his partiality for a certain Hagano, had aroused some irritation; and, supported by many of the clergy and by some of the most powerful of the Frankish nobles, Robert took up arms, drove Charles into Lorraine, and was himself crowned king of the Franks at Reims on June 29, 922. Collecting an army, Charles marched against the usurper, and on June 15 923, in a stubborn and sanguinary battle near Soissons, Robert was killed, according to one tradition in single combat with his rival.

Robert was married two times.

With Aelis he had two daughters:
1. Emma of France (894 – 935), married Rudolph, Duke of Burgundy.
2. Hildebrante of France (895 – 931), married Herbert II of Vermandois.

With Beatrix of Vermandois, daughter of Herbert I of Vermandois he had a son Hugh the Great, duke of the Franks, and his grandson was Hugh Capet, king of France.