The brook originates in eastern Denmark and flows through a chain of ponds along the border between Hiram and Sebago.

[9] Subsequent shoreline development with residences and seasonal cabins has caused increased algal blooms in the pond.

Hancock Brook downstream of Middle Pond forms the town line between Hiram to the west and Sebago to the east.

Hancock Brook is entirely within the town of Hiram after overflowing a dam at the southwest corner of Barker Pond.

[1] A granite masonry arch railroad bridge crossed the brook 1 mile (1.6 km) downstream of Rankins Mill.