Located in Fulton County, Broadalbin rests at the south end of Great Sacandaga Lake. The east town line is the border of Saratoga County. The village of Broadalbin is on the western side of the town and extends west into the town of Mayfield. The town is partially in the Adirondack Park.
Broadalbin is one of the first towns organized in the present county of Fulton, having been formed from a portion of Caughnawaga. was part of the Sacandaga Patent of 1741.
Castle Cumberland was a short-lived fortification in the town during the American Revolution.
When the Great Sacandaga Lake was created in 1930, some of the town's land was covered with water, including the Sacondaga Vlaie, a broad expanse of marshy land.
Broadalbin is abundantly watered by numerous creeks and small streams flowing in all directions throughout the town, chief among which is Kennyetto creek - often, incorrectly, called Fly creek, Fonda's creek, and sometimes Little Sacondaga. The creek was named from the fact that, after rising in Greenfield, Saratoga county, near Maxon hill, and running across Broadalbin into Mayfield, it returns and enters the Sacondaga river at Fish House, not more than three miles from its source.
New York State Route 29 crosses the center of the town, leading east to Saratoga Springs and west to Johnstown.