17.2% of the population in Mamasa Regency is Muslim.

The Muslim population in Mamasa Regency, as of December 31, 2023, was recorded at 28,509 individuals. This represents an increase of 293 individuals compared to the previous year's reported figure of 28,216.

According to data from the Directorate General of Population and Civil Registration (Ditjen Dukcapil) of the Ministry of Home Affairs, the proportion of Muslims in this regency/city reached 17.2 percent of the total population in 2023, which numbered 165,780 individuals.

Considering the distribution across the districts in West Sulawesi, the proportion of the Muslim population in Mamasa Regency ranks fifth.

The following is a list of the population of West Sulawesi by religion in 2023:

* Protestant: 124,398 (75.04%)
* Islam: 28,509 (17.2%)
* Indigenous Beliefs: 5,439 (3.28%)
* Catholic: 5,104 (3.08%)
* Hindu: 2,327 (1.4%)
* Buddhist: 3 (0.0%)
* Confucian: 0 (0.0%)

Compared to other regions in West Sulawesi, the number of Muslims in this regency/city ranks fifth.

Other regions with the highest number of Muslims are Polewali Mandar Regency (481,388 individuals), Mamuju Regency (242,559 individuals), Majene Regency (185,625 individuals), and Mamuju Tengah Regency (119,098 individuals).