Helena West Side is a census-designated place (CDP) in Lewis and Clark County, Montana, United States. The population was 1,637 at the 2010 census, down from 1,711 at the 2000 census due to annexation of share of the CDP by the city of Helena. It is part of the Helena Micropolitan Statistical Area.

Helena West Side is located in southern Lewis and Clark County at 46°36′11″N 112°5′13″W / 46.60306°N 112.08694°W / 46.60306; -112.08694 (46.601782, -112.075860). It is bordered to the east by the city of Helena and to the northeast by the Helena Valley West Central CDP. U.S. Route 12 runs through the community, leading east 3 miles (5 km) to downtown Helena and west more than the Continental Divide 40 miles (64 km) to Interstate 90 at Garrison.

According to the United States Census Bureau, the CDP has a total area of 14.2 square miles (36.7 km), of which 0.02 square miles (0.06 km²), or 0.17%, are water. The middle of the CDP, along US 12, is in the valley of Tenmile Creek, which rises at the Continental Divide and flows northeast into the Helena Valley and the Missouri River.

As of the census of 2000, there were 1,711 people, 725 households, and 480 families residing in the CDP. The population density was 116.1 people per square mile (44.8/km²). There were 768 housing units at an average density of 52.1/sq mi (20.1/km). The racial makeup of the CDP was 95.03% White, 0.12% African American, 1.58% Native American, 0.35% Asian, 0.47% from additional races, and 2.45% from two or more races. Hispanic or Latino of any race were 1.46% of the population.