Briefly, from 1241 until 1242, castellan of Dover Castle and Keeper of the Coast (later called Lord Warden of the Cinque Ports).

In 1243 he was granted land by the River Thames on the Strand near the City of London, where he built the Savoy Palace.

[3] As a younger son of a noble house, Peter started his career in the church, obtaining appointments in dioceses under the influence of his family.

[6] Peter also held the offices of canon at Lyon and of provost at Aosta and Geneva, before retiring from church life in 1234.

[4] Upon the death of his father, Peter demanded substantial portions of the county from his eldest brother Amadeus.

The brothers met at Chillon in 1234, where they negotiated a settlement which recognized Amadeus as the head of the house.

The younger Simon de Joinville, another of Agnes's half-brothers, would provide the conduit by which Burgundian knights would serve England both in Gascony and Wales.

When the resulting conflict was concluded in 1237, Amadeus forced William to sign a treaty which required Geneva to pay 20,000 marks and the castle of Arlod.

[10] On 29 May 1244, Cossonay similarly surrendered significant territories to Peter and Amadeus, retaining them only under the overlordship of Savoy.

He continued to gain control of key towns and trade routes throughout the Pays de Vaud, often by enfeofing them to the younger sons of the previous rulers.

[12] One scholar suggests that French is the language of western Switzerland due partly to Peter's extensive conquests in the region.

[14] On 25 September 1241 he was granted the Honour of the Eagle and wardship of John de Warenne, 6th Earl of Surrey bringing much land in Sussex and the south coast of England.

[3] Peter of Savoy played an important role in the events which led to the Provisions of Oxford in England in 1258 which would lead to the Second Barons' War.

These oath takers would form the core of the baronial movement supporting reform, and were “Richard de Clare, 6th Earl of Gloucester; Roger Bigod, 4th Earl of Norfolk; Simon de Montfort, 6th Earl of Leicester; Peter of Savoy; Hugh Bigod; John fitz Geoffrey; and Peter of Montfort.” Peter of Savoy sided with the reforming barons in order to reduce the political influence of the Lusignan half brothers of King Henry III who were in the view of Peter and his niece, the Queen Eleanor of Provence exerting undue influence at court.

Peter and Eleanor of Provence had gathered an army in Flanders to invade England to restore King Henry III to his throne.

[24] These statutes included the provision that his judges not delay justice which is attributable to the Magna Carta in England[3] Peter came into conflict with Rudolf of Habsburg, and Henri of Raron, Bishop of Sion.

Peter died without a male heir in 1268, at the castle of Pierre-Châtel, now in Virignin, and was buried in Hautecombe Abbey.