Garcinia buchananii Baker (Family,Cluciaceae/Guttiferae) is an underutilized indigenous fruit tree that produces edible fruits that are used as both food and medicine in tropical Africa. This study evaluated the physical and chemical characteristics of G. buchananii fruits collected from Uganda and Rwanda. Ripe fruits were harvested during their peak seasons in Masaka and Bugesera Districts in Uganda and Rwanda, respectively. The fruits were analyzed for physical characteristics including; fruit weight, fruit size (that is length and width), number of seeds per fruit, seed weight, seed dimensions(length, width and breadth); chemical characteristics (pH and titratable acidity), proximate composition (moisture content, protein, fat, dietary fibre, carbohydrates and energy), mineral composition (K, Na, Ca, Mg, Ca, Fe, Zn, Cu), and bioactive components (total phenolic compounds, flavonoids and anthocyanins; and antioxidant activity). Data were statistically analyzed using a student T-test (p≤0.05). The results indicated that fruit weight and pulp content ranged from 6.3±1.3-9.5±2.8g and 54.1±10.6- 81.1±6.5%, respectively. Titratable acidity of the pulp ranged from 6.1±0.8 to 7.1±0.1 %. Nutritionally, dietary fibre, vitamin C, iron and zinc ranged from 20.0±0.4 -22.6±1.8 g/100g, 32.8±3.2-42.0±3.3 mg/100g, 4.8±0.2 - 6.5±0.8 mg/100g and 1.1±0.0 -2.5±0.1 mg/100g, respectively. The total phenolic compounds and antioxidant activity ranged from 996.7±50.5 - 1147.5±47.4 mg/g GAE (Garlic Acid Equivalent) and 8.0±0.2- 8.4±0.1 mg/100g AAE (Ascorbic Acid Equivalent) as IC50, respectively. There was a significant difference (p≤0.05) in the physical characteristics (weight, length, width and breadth), nutritional composition and bioactive components of the fruit samples of the two countries. Assessment of the nutrients indicated that the pulp was rich in vitamin C, iron, zinc, copper and dietary fibre. The pulp also contained phenolic compounds with antioxidant activity. The seeds had 6-24% crude oil content with palmitic, stearic, oleic and linoleic as major fatty acids. The total unsaturated fatty acids in the seed oil ranged from 58.4-59.5%. Although this finding showed significant differences (P≤0.05) in the physical and chemical of G. buchananii fruit from Uganda and Rwanda, the nutritional composition and bioactive component information has shown the potential of the fruits for processing into high-value nutraceuticals.