"[citation needed] It runs for approximately 95 kilometres, draining an area in the Caledonia Highlands, an extension of the Appalachian Mountains, inland from the Bay of Fundy.

The upper two thirds of the Kennebecasis River passes through pastoral rural countryside consisting of Acadian mixed forest and various agricultural areas, notably dairy farms around Sussex.

Once a minor dormitory suburb of the Saint John area, the towns of Rothesay and Quispamsis constitute a moderately-sized population centre with some commercial development.

Several controversial proposals have been made in recent decades to build a highway bridge over the Kennebecasis River to the Kingston Peninsula however this has been rejected by numerous provincial governments citing financial pressures as well as the likelihood of suburban sprawl occurring in this farming area as a result.

The Kennebecasis River valley communities have rich histories; many were settled by Loyalists in the 1780s and 1790s who traveled upriver from Saint John to land grants offered by the British government.