Both Roger and Robert may have 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 six lordships in Essex, 117 in Suffolk and 187 in Norfolk.
Bigod's base was in Thetford, Norfolk where he founded a priory later donated to the great monastery at Cluny. In 1101 he further consolidated his power when Henry I granted him licence to build a castle at Framlingham, which became the family seat of power until their downfall in 1307. Another of his castles was Bungay Castle, also in Suffolk. Both these were improved by successive generations.
In 1069 he, along with Robert Malet and Ralph de Gael (the then Earl of Norfolk), defeated Sweyn Estrithson (Sweyn II) 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. He acquired further estates through his influence in local law courts.
In the Rebellion of 1088 he joined other Anglo-Norman barons 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.
In 1100, Robert Bigod (Bigot) was one of the King's witnesses recorded on the Charter of Liberties, an important precursor to the Magna Carta of 1215.
In 1101 there was another attempt to bring in Robert of Normandy by unseating Henry I, but this time Roger Bigod stayed loyal to Henry.
He died on September 9, 1107 and is buried in Norwich. Upon his death there was a dispute between the Bishop of Norwich, Herbet Losinga, and the monks at Thetford Priory, founded by Bigod. The monks claimed that Roger's body, along with those of his family and successors, was due to them as part of the foundation charter of the priory (as was common practice at the time). The issue was apparently resolved when the Bishop of Norwich stole the body in the middle of the night and dragged it back to Norwich.
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, 1st Earl of Norfolk, who later became Earl of Norfolk. He also had 3 daughters: Gunnor, who married Robert, Lord of Rayleigh; Cecily, who married William d'Aubigny "Brito"; and Maud, who married William d'Aubigny "Pincerna", and was mother to William d'Aubigny, 1st Earl of Arundel.