Hubert Walter was the son of Hervey Walter and his wife Maud de Valoignes, one of the daughters (and co-heiresses) of Theobald de Valoignes, who was lord of Parham in Suffolk. Walter was one of six brothers. The eldest brother, Theobald Walter, and Walter himself, were helped in their careers by their uncle, Ranulf de Glanvill.[a] Glanvill was the chief justiciar for Henry II; and was married to Maud de Valoignes' sister, Bertha. Walter's father and paternal grandfather held lands in Suffolk and Norfolk, which were inherited by Theobald. A younger brother, Osbert, became a royal justice and died in 1206. Roger, Hamo (or Hamon) and Bartholomew only appear as witnesses to charters.
Walter's family was from West Dereham in Norfolk, which is probably where Walter was born. Walter first appears in Glanvill's household in a charter that has been dated to 1178, although as it is undated it may have been written as late as 1180. His brother Theobald also served in their uncle's household. Walter's gratitude towards his aunt and uncle is shown in the foundation charter of Walter's monastery in Dereham, where he asks the foundation to pray for the "souls of Ranulf Glanvill and Bertha his wife, who nourished us". Earlier historians asserted that Walter studied law at Bologna, based on his name appearing in a list of those to be commemorated at a monastery in Bologna in which English students lodged. Modern historians have discounted this, as the list also includes benefactors, not just students; other evidence points to the fact that Walter had a poor grasp of Latin, and did not consider himself to be a learned man. However, this did not mean that he was illiterate, merely that he was not "book-learned", or educated at a university. His contemporary, the medieval writer Gerald of Wales said of Walter that the Exchequer was his school.