Nine selected S 3 papaya breeding lines were evaluated for their antioxidant properties and fruit quality. The 14 antioxidant properties and fruit quality traits measured in this study showed significant genotypic differences. KK80 showed the highest ascorbic acid content (114 ± 20 mg/100 ml), antioxidant activity (8.0 ± 1.3 µmol ascorbic acid equivalents/g fresh weight [FW]), and total phenolic compounds (72.2 ± 5.8 mg gallic acid equivalents/100 g FW). KD7 contained the highest amounts of total flavonoid (21.0 ± 5.8 mg catechin equivalents/100 g FW), lycopene (11.0 ± 1.7 mg/100 g FW), and β-carotene (10.0 ± 1.7 mg/100 g FW). The significant variation in antioxidant properties and fruit quality clearly shows the potential value of selected papaya breeding lines as new cultivars and parents in a breeding programme. Lycopene had a positive correlation with β-carotene (r = 0.62). Fruit size showed a negative correlation with total phenolic compounds (r = −0.64), antioxidant activity (r = −0.45), and ascorbic acid (r = −0.44). Flesh colour as hue angle was negatively correlated to lycopene (r = −0.67), suggesting that lycopene may be estimated indirectly by using the hue angle.