Granby is a town in Hampshire County, Massachusetts, United States. The population was 6,110 at the 2020 census. It is part of the Springfield, Massachusetts Metropolitan Statistical Area. The census-designated place of Granby corresponds to the main village of Granby in the center of the town.

The town is named in honor of John Manners, Marquess of Granby, a hero of the Seven Years' War. The place name, Granby, refers to a village in Nottinghamshire, taking its name from the personal name Gráni and the Old English suffix bȳ, denoting a farmstead or settlement.

Granby was once part of Hadley, as were other towns, as part of Hadley Equivalent Lands. Old Hadley was first settled in 1659 by people from Hartford and Wethersfield, Connecticut. These settlers left Connecticut because of religious differences within their communities.

John Pynchon was commissioned to buy wilderness land for their new community. In 1658, Pynchon negotiated a deed with three Norwottuck sachems: Chickwalloppe (alias Wawhillowa), Umpanchela (alias Womscom), and Quonquont (alias Wompshaw). The deed reserved land for a cornfield for the Norwottuck and promised rights to hunt, fish and set up wigwams within the negotiated land. Ownership was transferred to the settlers and confirmed by the General Court. These original boundaries include part of present-day Granby.

In August 1662, Pynchon negotiated a deed with Awonunsk, her husband Wequagon, and her son Squomp, for land also in present-day Granby, South Hadley and Belchertown. Ownership was transferred to the settlers and Awonunsk and her family were paid in 150 fathoms of wampum (approximately 54,000 wampum beads), 10 coats, and 2 yards of cloth, among other items. The deed also promised rights for the Norwottuck to hunt, fish, collect wood, and set up wigwams on the commons.

Granby was settled in 1727. In November 1727, residents of what are now South Hadley and Granby petitioned the General Court to form a precinct within the Town of Hadley. This petition was granted on July 4, 1732, creating Hadley's South Precinct. In 1753, the precinct was granted district status. From 1751 through 1761, the district was deadlocked over whether to build a new meetinghouse west of Cold Hill, in present-day South Hadley, or to its east, in present-day Granby. In the Summer of 1761, the district's west side began constructing a meetinghouse without town meeting approval. In response, a group of 27 east side residents and three west side residents tore down the partially constructed meetinghouse.

In 1762, the General Court split the district into an east and west parish, each with its own meetinghouse. With tensions between the parishes still high, the General Court set off the east parish as the Town of Granby, being incorporated on June 11, 1768.

Granby is one of only three towns in Massachusetts whose local telephone service is not furnished by the former Bell System as Granby has maintained its own service, Granby Telephone & Telegraph, since 1903. The other two such towns are Richmond and Hancock, both in Berkshire County.