Sinan Pasha occupied a position at the intersection of two of the most powerful institutions in the 16th-century Ottoman state. He was the younger brother of Rüstem Pasha, who served twice as Grand Vizier and was married to Mihrimah Sultan, daughter of Suleiman the Magnificent. And he commanded the Ottoman fleet during a period of Mediterranean dominance that followed the great victories of his predecessor Barbaros Hayrettin Pasha. His decision to commission a mosque in Beşiktaş, a district closely associated with the navy, and to engage Mimar Sinan for the project, placed him firmly in the tradition of Ottoman grandees who understood that architectural patronage was a form of legacy-building. Sinan Pasha died in 1553. Work on the mosque began after his death and was completed the following year.

Mimar Sinan's design for the Sinan Pasha Mosque is compact by the standards of his later imperial commissions, but structurally inventive. The 12.6-meter dome is supported on six arches resting on two free-standing hexagonal piers — an arrangement that creates an unusually open interior for a mosque of this scale. Scholars have compared the structural logic to the earlier Üç Şerefeli Mosque in Edirne, built between 1437 and 1447, in which the same hexagonal-pier solution supports a wide central dome. Sinan was working within and extending an established tradition, not breaking from it. The mosque is built of alternating layers of ashlar stone and brick, a construction method common in Byzantine and early Ottoman architecture that gives the exterior a distinctive banded texture. The original painted interior decoration has not survived, leaving the space sober and geometric.

The forecourt of the Sinan Pasha Mosque is enclosed on three sides by a madrasa — a school — with a shed roof supported on short columns. At the center of the courtyard sits a rectangular drinking fountain, its date of 1555–56 recorded in Turkish around the white marble basin. The original north facade had a double portico: an outer covered walkway and an inner one with five domes. In 1749 the inner portico was incorporated into the prayer hall, expanding the interior space at the cost of the original architectural layering. The minbar — the pulpit from which the Friday sermon is delivered — is simple white marble. The bath-house that formed part of the original endowment was demolished in 1957. What remains is a coherent mid-16th-century Ottoman ensemble, modest in ambition by the standards of Sinan's larger works, but elegant in its proportions.

The mosque sits in a neighborhood that still feels connected to the water. Beşiktaş is a busy transit hub on the European Bosphorus shore, with ferries arriving from the Asian side and buses radiating inland. The türbe of Barbaros Hayrettin Pasha — Barbarossa, the corsair-turned-admiral who built Ottoman naval supremacy in the Mediterranean — stands just across the street from the mosque, maintained as a monument to a man who came to symbolize Ottoman sea power. Together, the mosque and the tomb form a small precinct of 16th-century naval memory embedded in the commercial noise of a 21st-century waterfront district. Mimar Sinan, who outlived both men he worked for and went on to build for a generation of patrons, would have recognized neither the traffic nor the ferry terminal. The mosque, though, he would recognize immediately.