In recent times, the diet and foraging behaviors of wild animals are influenced by anthropogenic foods since they often share their natural habitats with humans. We investigated the composition, preferred food item, contribution of anthropogenic food at garbage dump sites, and the seasonal effects on the diet of Lowe’s monkeys (Cercopithecus lowei) in the Duasidan Monkey Sanctuary, Ghana. We found that Lowe’s monkeys fed on 13 plant species, as well as anthropogenic foods and invertebrates. The composition of plant diet changed seasonally: Lowe’s monkeys relied more on buds in the dry season while they consumed more fruits in the wet season. However, anthropogenic food was a major component of the diet for both wet (34.8%) and dry seasons (41.3%), suggesting that the monkeys consistently rely on anthropogenic food throughout the year. Nevertheless, we did not observe any conflict between monkeys and local people. The results suggest that Lowe’s monkeys heavily rely on anthropogenic food at human garbage dumps while they maintain a part of their foraging activities in the wild, indicating a need for the proper management of garbage as well as the protection of the natural habitats of Lowe’s monkeys in the Duasidan Monkey Sanctuary, Ghana.