Tuna meat (Thunnus atlanticus -blackfin tuna) and purslane flour (Portulaca oleracea L.), which contain high protein and polyunsaturated fatty acids but are low fat and cholesterol, are used to substitute beef and tapioca flour to produce quality meatballs. This study aims to determine the effect of substituting beef and tapioca flour with tuna meat and purslane flour on meatballs' chemical, physical, and sensory quality. The beef was substituted with 40% tuna meat, and tapioca flour was substituted with 0, 10, and 20% purslane flour. The data obtained were analysed using a complete randomised design, with three treatments and five replications, respectively, and further tested with the Duncan test. The results showed that increasing the level of purslane flour can increase (P < 0.01) the chemical quality (water, protein, fat, ash, and omega-3) but decrease (P < 0.01) the cholesterol of the meatballs. Physical quality (water holding capacity and sensory quality (colour) of meatballs were increased (P < 0.01), but taste and acceptability were decreased (P < 0.01). It can be concluded that substituting beef and tapioca flour with tuna meat and purslane flour can increase the chemical and physical quality.