William Bertrand (died 28 July 1094),[a] was the count and margrave of Provence from 1051 to his death.
He succeeded his father Fulk Bertrand on his death in that year, but did not receive the margravial title at first, for it went to his uncle Josfred.
In 1081, he renounced his allegiance to the Holy Roman Emperor and swore fealty to the Papacy.
When William Bertrand died, the margraviate was inherited by Raymond IV of Toulouse.
William Bertrand's daughter, Adelaide, inherited Forcalquier from her uncle, Geoffrey II of Provence.