Near the intersection with Lakewood Street, NY 112 leaves the village of Patchogue, entering the town of Brookhaven.

NY 112 crosses over the Sunrise, continuing north as Medford Avenue as the four-lane boulevard it was prior to the interchange.

NY 112 passes Tremont Elementary School before crossing Greenport Road, continuing northward into the census-designated place of Medford.

After crossing under the tracks, NY 112 continues northeast through Medford, entering interchange 64 of the Long Island Expressway (I-495) and expanding to four lanes once again before an intersection with CR 16 (Horse Block Road).

The route returns to two lanes after CR 16, passing east of Blue Ridge Golf Club and Holy Sepulchre Cemetery.

[4] After the bend, NY 112 continues through Brookhaven, crossing a large shopping plaza into the census-designated place of Port Jefferson Station.

[8][9] Most of the old stage road was acquired by the state of New York in 1913; however, the section within the Patchogue village limits did not become state-maintained until the 1920s.

This project included tilting the curved embankment of the southbound lane, which has created a series of floods in moderate to heavy rainstorms.