98.8% of the population in Ogan Ilir Regency is Muslim.

The Muslim population in Ogan Ilir Regency, as of December 31, 2023, was recorded at 438,260. This figure represents an increase of 10,322 individuals compared to the previous year's reported figure of 427,940.

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 98.8 percent of the total population in 2024, which numbered 443,360.

Considering the distribution across the districts of South Sumatra, the proportion of Muslims in Ogan Ilir Regency ranks seventh.

The following is a list of the population of South Sumatra by religion in 2023:

* Islam: 438,257 (98.85%)
* Protestant: 777 (0.18%)
* Buddhist: 298 (0.07%)
* Catholic: 114 (0.03%)
* Hindu: 13 (0.0%)
* Confucian: 6 (0.0%)
* Indigenous Beliefs: 4 (0.0%)

Compared to other regions in South Sumatra, the Muslim population in this regency/city ranks seventh out of 17 regencies/cities in South Sumatra province.

Other areas in South Sumatra with the largest Muslim populations are Palembang City (1,657,373), Banyuasin Regency (833,934), Ogan Komering Ilir Regency (760,994), Musi Banyuasin Regency (693,281), Ogan Komering Ulu Timur Regency (649,536), Muara Enim Regency (632,396), Lahat Regency (438,137), Ogan Komering Ulu Selatan Regency (418,232), Musi Rawas Regency (412,458), and Ogan Komering Ulu Regency (373,976).