[4][5] The area entered the written record in 1614, when Captain John Smith explored the coast of New England and described an encounter of his ship with four Native Americans in a canoe at Quonahasit, two of whom were shot by the Europeans.

The town's name came from the Massachusett word "Conahasset," possibly meaning "long rocky place"[8] or "fishing promontory.

[14] It is bordered on the west by Hingham, on the northwest by Hull, on the north and northeast by Massachusetts Bay and on the east and south by Scituate.

Cohasset is located on the "corner" of the South Shore, where greater Boston Harbor ends and Massachusetts Bay begins.

Near the center of the coast lies Little Harbor, a large inlet divided from the ocean by Beach Island.

A large portion of the southwestern part of town is occupied by Wompatuck State Park (formerly the Hingham Naval Ammunition Depot Annex), and the Whitney & Thayer Woods Reservation.

The climate in this area is characterized by hot, humid summers and generally mild to cool winters.

Additionally, Cohasset averages 14.2" of snow in its snowiest month (February) and 48.3" for the year.

[16] On the national level, Cohasset is a part of Massachusetts's 9th congressional district, and is currently represented by Bill Keating.

[17] The town is patrolled on a secondary basis by the First (Norwell) Barracks of Troop D of the Massachusetts State Police.

The current Board of Selectmen consists of Kevin McCarthy, Chair, Paul Schubert, Vice-Chair, and Diane Kennedy, Steve Gaumer, and Jack Keniley.

Emergency services are also provided by the town, with patients taken to the South Shore Hospital in Weymouth.

Members of the Cohasset School Committee are Jeanne Astino(Chairman), Katie Dugan(Vice-Chairman), Ellen Maher, Barbara Stefan and Amanda Zani.

Cohasset's athletics teams are known as the Skippers, and their colors are navy blue and white.

They compete in the South Shore League, and their chief rival is Hull High School.

The athletic programs offered to Cohasset High School students include Baseball, Ice Hockey, Basketball, Cross Country, Tennis, a Competitive Debate Team, Football (which won the 2014 Division VI Super Bowl, and made it to the 2013 Division VI Super Bowl, but lost), Soccer, Competitive Swimming, Track and Field, Sailing, Ski Team, Wrestling and Lacrosse.

Route 228 runs along the border with Hingham, crossing the Weir River into Hull.

The MBTA's commuter rail Greenbush Line has a Cohasset station off Route 3A, just east of a cemetery.