Guy II of Ponthieu (–25 December 1147) was the son of William III of Ponthieu and Helie of Burgundy.
He succeeded his father as Count of Ponthieu before 1129; this was during William's lifetime. Around 1137, he founded the Cistercian Valloires Abbey.
He joined the Second Crusade under King Louis VII of France, and died of a disease on 25 December 1147 in Ephesus.
He was succeeded by his son John I of Ponthieu.
His wife was called Ida; he had three children with her: