Trumbull's land was originally home to the Golden Hill Paugussett people for thousands of years before English settlers arrived in 1639 as part of the town of Stratford, in an area then known as Pequonnocke. Families gradually pushed further from the coast, and by the late 1780s, the northern section of Stratford, known as North Stratford, began petitioning the Connecticut General Assembly for independence. That independence was finally granted in October 1797, and the new town took the name Trumbull, honoring Jonathan Trumbull, the Revolutionary War governor of Connecticut.

Through the 1800s, farming and small industry, including gristmills and paper mills along the Pequonnock River, sustained the town's economy. One notable local figure was aviation pioneer Igor Sikorsky, who lived in Trumbull during the years he designed, built, and flew fixed-wing aircraft before putting the helicopter into mass production for the first time in history.

The 20th century brought major change. In 1964, Trumbull Mall opened as Connecticut's first enclosed shopping mall, and in 1989 the town partnered with the state to preserve hundreds of acres of the Pequonnock River Valley as protected open space rather than let it be developed.