He was the son of Albert I, and Ermengarde, daughter of Charles, Duke of Lower Lorraine.
He assisted his mother's brother-in-law, Lambert I, Count of Louvain in his fight against Baldrick II, Bishop of Liege in 1012.
In 1015, he participated in the Battle of Florennes where Lambert was killed.
Although some researchers have said that Robert died in the same battle, he survived because he is again mentioned in 1018 in an imperial diploma.
After his death, he was succeeded as count of Namur by his younger brother, Albert II.