His main patron was the Albanian Grand Vizier Kemankeş Kara Mustafa Pasha who secured Köprülü Mehmed's appointment as mirahor.

There was a political plot to unseat the reigning Sultan Mehmed IV led by important viziers including the Grand Mufti (Şeyhülislam) Hocazade Mesut Efendi.

The Mother Sultana Turhan Hatice conducted consultations and the most favored candidate for the post of Grand Vizier came out as the old and retired but experienced Köprülü Mehmed Pasha.

As the Grand Vizier, his first task was to advise Sultan Mehmed IV to conduct a life of hunts and traveling around the Balkans and to reside in the old capital of Edirne, thus stopping his direct political involvement in the management of the state.

The Greek Orthodox Patriarch of Constantinople was proven to be in treasonous contacts with the enemies of Ottoman state and Köprülü Mehmed Pasha approved of his execution.

The Sultan gave the Grand Vizier the absolute authority over the life and property of the Ottoman government and people and assured him that anyone who opposed him for any purpose could be executed for disobeying the order.

However, Sultan Mehmed IV remained steadfast in his support for Köprülü and dispatched an army against the rebels under the command of Murtaza Pasha, who was then guarding the Safavid frontier.

[2] While stationed in Köprü in Anatolia, he married Ayşe Hatun (Hanım), daughter of Yusuf Ağa, a notable originally from Kayacık, a village of Havza in Amasya.

Yusuf Ağa was a voyvoda (tax-farmer)[9] who built a bridge in Kadegra, that thus became Köprü, from which the family name of Mehmed (who was originally stationed there, and where he was sanjak-bey)[10] was taken.