Sixty percent of West Kalimantan's population was Muslim in June 2021.

The Directorate General of Population and Civil Registration (Dukcapil) of the Ministry of Home Affairs recorded that the population of West Kalimantan was 5.46 million as of June 2021. Of this number, 3.29 million people, or 60.14% of the province's population, are Muslim.

The population of West Kalimantan who are Catholic numbers 1.21 million, or 22.15% of the total population. The population of the province, known as the "Province of a Thousand Rivers," who are Christian numbers 631,790, or 11.57%.

Furthermore, 316,570 people (5.8%) of West Kalimantan's population are Buddhist, 14,740 (0.27%) are Confucians, 2,820 (0.05%) are Hindu, and 1,380 (0.03%) adhere to indigenous beliefs.

Based on gender, 2.81 million (51.41%) of West Kalimantan's population are male, and 2.65 million (48.59%) are female.

According to marital status, 2.72 million (49.77%) of West Kalimantan's population are unmarried, and 2.49 million (45.63%) are married. There are 65,950 (1.21%) widowed individuals, and 185,230 (3.39%) divorced individuals.

West Kalimantan is one of the provinces in Kalimantan with a land area of 147,307 square kilometers (km) and a population density of 37 people/km². Administratively, the province is divided into 12 regencies and 2 cities, comprising 174 districts, 2,031 villages, and 99 urban villages.