He was the son of William the Conqueror's mother Herleva, and Herluin de Conteville. Although he was an ordained Christian cleric, he is best known as a warrior and statesman. He found ships for the invasion of England and is one of the very few proven Companions of William the Conqueror known to have fought at the Battle of Hastings in 1066. The Bayeux Tapestry, probably commissioned by him to adorn his own cathedral, appears to labour the point that he did not actually fight, that is to say shed blood, at Hastings, but rather encouraged the troops from the rear. The Latin annotation embroidered onto the Tapestry above his image reads: "Hic Odo Eps (Episcopus) Baculu(m) Tenens Confortat Pueros", in English "Here Odo the Bishop holding a club strengthens the boys". It seems that his clerical status forbade him from using a sword. He was accompanied by William the carrier of his crozier and a retinue of servants and members of his household. In 1067 Odo became earl of Kent, and for some years he was a trusted royal minister. On some occasions when William was absent (back in Normandy), he served as de facto regent of England, and at times he led the royal forces against rebellions (e.g. the Revolt of the Earls): the precise sphere of his powers is not certain, however. There are also other occasions when he accompanied William back to Normandy. During this time Odo acquired vast estates in England, larger in extent than any one except the king: he had land in 23 counties, primarily in the south east and in East Anglia.

In 1076 Odo was tried in front of a large and senior assembly over the course of three days at Penenden Heath in Kent for defrauding the Crown and the Diocese of Canterbury. At the conclusion of the trial he was forced to return a number of properties and his assets were re-apportioned. In 1082 he was suddenly disgraced and imprisoned for having planned a military expedition to Italy. His motivations are not certain. Chroniclers writing a generation later said Odo desired to make himself Pope, but the contemporary evidence is ambiguous. Whatever the reason, Odo spent the next five years in prison, and his English estates were taken back by the king, as was his office as Earl of Kent: Odo was not however deposed as Bishop of Bayeux. William, on his deathbed in 1087, was reluctantly persuaded by his brother Robert, Count of Mortain to release Odo. After the king's death Odo returned to his earldom and soon organized a rebellion in support of William's son Robert Curthose, who had been made Duke of Normandy. The Rebellion of 1088 failed and William Rufus permitted Odo to leave the kingdom. Afterwards, Odo remained in the service of Robert in Normandy. He joined the First Crusade, and started in the duke's company for Palestine, but died on the way at Palermo in January or February 1097.

Little good is recorded of Odo. It was recorded that his vast wealth was gained by extortion and robbery. His ambitions were boundless and his morals lax. However, like many prelates of his age, he was a patron of learning and the arts. He was also a great architect. He founded the Abbaye de Troarn in 1059 and rebuilt the cathedral of his see, and is likely to have commissioned the celebrated Bayeux tapestry. He may also have sponsored an early version of The Song of Roland. More certain is his development of the cathedral school in Bayeux, and his patronage of a number of younger men who later became prominent prelates.