Roger came from a fairly obscure family of poor knights in Normandy. Robert Bigod, who was probably Roger's father, acquired an important position in the household of William, duke of Normandy (the later William I of England), due, the story goes, to his disclosure to the duke of a plot by the duke's cousin William of Mortain.
Robert or Roger, or perhaps even both, fought at the Battle of Hastings, and afterwards they were rewarded with a substantial estate in East Anglia. The Domesday Book lists Roger as holding 6 lordships in Essex, 117 in Suffolk and 187 in Norfolk.
In 1069 he, along with Robert Malet and Ralph de Gael (the then Earl of Norfolk), defeated Sweyn I of Denmark near Ipswich. After Ralph de Gael's fall in 1074, Roger was appointed Sheriff of Norfolk and Suffolk, and acquired many of the dispossessed earl's estates. For this reason he is sometimes counted as Earl of Norfolk, but he probably was never actually created earl.
In 1087 he joined in a rebellion against William II, who, it was hoped, was to be deposed in favour of Robert Curthose, Duke of Normandy. He seems to have lost his lands after the rebellion had failed, but got them back again.
For some time he was thought to have two wives, Adelaide/Adeliza and Alice de Tosny. It is now believed these were the same woman, Adeliza(Alice) de Tosny(Toeni,Toeny). She was the sister and coheiress of William de Tosny, Lord of Belvoir.
He was succeeded by his eldest son, William Bigod, and, after he drowned in the sinking of the White Ship, by his second son, Hugh Bigod, who later became Earl of Norfolk. He also had 3 daughters: Gunnor, who married Robert, Lord of Rayleigh; Cecily, who married William d'Albini; and Maud, who married William d'Albini "Pincerna", earl of Arundel.