Mulberries, Morus spp., grow in different growing regions of Turkey with a high diversity providing an opportunity to select superior accessions. The goal of the study was to determine the differences in phytochemical components and horticultural characteristics between white and black mulberry accessions in the Igdir province. Fruits of black and white mulberries collected from Igdir province were assayed for various horticultural characteristics including berry width, berry length, berry weight, and berry peduncle length. Samples were also assayed for vitamin C, organic acids (citric, tartaric, malic, succinic, and fumaric), sugars (glucose and fructose), phenolic acids (catechin, rutin, quercetin, chlorogenic, ferulic, o-coumaric, p-coumaric, caffeic, syringic, vanillic, and gallic acids), and antioxidant capacity [Trolox equivalent antioxidant capacity (TEAC) assay]. Differences (P < 0.05) were noted between accessions in berry length and berry weight. Malic acid was found to be the predominant organic acid regardless of species. Rutin (for black mulberry) and chlorogenic acid (for white mulberry) were the predominant phenolic acids. Black mulberry had higher glucose and fructose content than white mulberry. Analysis showed that black mulberry had higher content of tartaric acid, malic acid, TEAC, fructose, glucose, catechin, rutin, quercetin, o-coumaric acid, and caffeic acid compared with white mulberry (P < 0.01); however, white mulberry had higher content of succinic acid, vitamin C, chlorogenic acid, ferulic acid, p-coumaric acid, syringic acid, and gallic acid (P < 0.01). Our results provide a reference for further studies of mulberry fruits in detection of organic acids, sugars, antioxidant capacity, and phenolic compounds. Also, it is clear that we need standardized testing, extraction, and analysis protocols to compare genotypes grown in different countries.