St. Bernard was laid out in 1851 at the intersection of Main Street (now Vine Street, Cincinnati), the Miami and Erie Canal, and the Cincinnati, Hamilton and Dayton Railway. The town was originally built up chiefly by Germans.
As of the census of 2010, there were 4,368 people, 1,869 households, and 1,090 families residing in the village. The population density was 2,818.1 inhabitants per square mile (1,088.1/km2). There were 2,128 housing units at an average density of 1,372.9 per square mile (530.1/km2). The racial makeup of the village was 80.0% White, 15.7% African American, 0.3% Native American, 0.7% Asian, 0.1% Pacific Islander, 0.9% from other races, and 2.3% from two or more races. Hispanic or Latino of any race were 1.9% of the population.
There were 1,869 households of which 29.9% had children under the age of 18 living with them, 37.2% were married couples living together, 15.4% had a female householder with no husband present, 5.7% had a male householder with no wife present, and 41.7% were non-families. 36.2% of all households were made up of individuals and 12.8% had someone living alone who was 65 years of age or older. The average household size was 2.33 and the average family size was 3.08.
The median age in the village was 38.2 years. 23.6% of residents were under the age of 18; 10% were between the ages of 18 and 24; 25.1% were from 25 to 44; 28.2% were from 45 to 64; and 13% were 65 years of age or older. The gender makeup of the village was 47.2% male and 52.8% female.