Antioxidants are diverse groups of biological compounds, including phenolic compounds, flavonoids, alkaloids, and terpenoids, which act as free radical scavenging. Fruits are the natural antioxidant resources that constitute principal dietary components. Therefore, identifying the type and amount of antioxidant compounds in different fruits and the factors affecting them is crucial to achieving a diet rich in antioxidants. The quality and quantity of antioxidant compounds in fruits are influenced by various factors such as climate, species and cultivars, fruit developmental stage, processing methods, and storage conditions. In horticulture, fruits are divided into three categories based on climatic origin, including temperate fruits (rich in anthocyanins and phenolic acids) such as apples, grapes, and berries, subtropical fruits (rich in flavonoids and phenolic acids) such as pomegranate and olives, and tropical fruits (rich in flavonoids and carotenoids) such as bananas and mangoes. Also, there is a significant variation in the quantity and quality of antioxidant compounds in a specimen of fruits, which can be the basis for selecting parents by breeders to achieve antioxidant-rich cultivars. The amount of phenolic compounds in fruits is related to the degree of fruit maturity or ripening, and usually, with increasing age, the amount of phenolic compounds increases. From a processing point of view, recently, the use of wine and olive industry waste products has been considered as a potential source of dietary or food preserving antioxidants. In this review, various antioxidant compounds in different fruits have been considered, and the factors affecting their quality and quantity are discussed.