Pepper is widely grown and sold in Rivers State, but few studies have compared multiple commonly consumed varieties concurrently using a common analytical protocol. Therefore, the purpose of this study was to identify and contrast the proximate, mineral, and phytochemical composition of various pepper cultivars in this state. The study was carried out in the nursery, and botanical garden of the Department of Plant Science and Biotechnology, Rivers State University, Port Harcourt, Nigeria. Seeds were planted in the nursery, and later transplanted into 10L capacity ploytene bags that were perforated at the bottom. Proximate, mineral and phytochemical analysis was carried out following standard methods, and the data collected were subjected to analysis of variance (ANOVA). Result showed that: bell pepper had the highest moisture content (12.40±0.14), ash content (10.20±0.14), protein content (14.88±0.00); phosphorus (8.58±0.00), flavonoid (12.31±0.01), carotenoid (1.82±0.02), and alkaloid (9.50±0.00); chili pepper had the highest fat content (8.91±0.00), fibre (20.00±0.00), carbohydrate (45.51±0.07), manganese (0.12±0.00), and calcium (26.51±1.14); and habanero peeper had the highest potassium content (8.27±3.69), sodium (12.22±0.05), tannic acid (2.00±0.00), and saponin (1.64±0.19). The different pepper varieties showed significant variations in their proximate, mineral, and phytochemical composition.