West Dennis is a census-designated place (CDP) in the town of Dennis in Barnstable County, Massachusetts, United States. The population was 2,242 at the 2010 census.

West Dennis is located in the southwest corner of the town of Dennis at 41°39′42″N 70°9′43″W / 41.66167°N 70.16194°W / 41.66167; -70.16194 (41.661753, -70.161975). It is bordered to the north by the CDP of South Dennis, to the east by Dennis Port, to the south by Nantucket Sound, and to the west by South Yarmouth.

According to the United States Census Bureau, the West Dennis CDP has a total area of 4.2 square miles (10.9 km). 3.3 square miles (8.5 km²) of it is land, and 0.97 square miles (2.5 km) of it (22.50%) is water.

In a typical year, West Dennis, Massachusetts temperatures fall below 50F° for 167 days per year. Annual precipitation is typically 43.5 inches per year (high in the US) and snow covers the ground 0 days per year or 0% of the year (the lowest in the US). It may be helpful to understand the yearly precipitation by imagining 9 straight days of moderate rain per year. The humidity is below 60% for approximately 27.6 days or 7.6% of the year.

The Ezra H. Baker Elementary School, named for Ezra Henry Baker, is found in West Dennis.

As of the census of 2000, there were 2,570 people, 1,279 households, and 698 families residing in the CDP. The population density was 301.6/km² (781.3/mi). There were 2,733 housing units at an average density of 320.7/km² (830.8/mi). The racial makeup of the CDP was 95.53% White, 2.37% African American, 0.54% Native American, 0.31% Asian, 0.43% from other races, and 0.82% from two or more races. Hispanic or Latino of any race were 0.93% of the population.