Born in 1642, Mehmed is the son of Turhan Sultan and the little brother of  Osman, Ibrahim's illegitimate son. Mehmed is the big brother of Sultan Süleyman II, Ayşe Sultan, Sultan Ahmed II, Beyhan Sultan, Şehzade Cihangir and Şehzade Orhan. He is the grandson of Kösem Sultan and ascends the throne after Ibrahim is killed in 1648. He has three cousins: Zeynep, daughter of Sultan Osman II, Kaya, daughter of Sultan Murad IV, and Selim, son of Sultan Murad IV 