This study evaluated the effects of dietary supplementation with nano- and micro-encapsulated polyphenol extract (PE) from olive leaves (OL) and olive mill wastewater (OMWW), respectively, on growth, carcass and meat quality traits in Podolian young bulls. Fifteen 12-month-old bulls were assigned to three groups: C (control); T1 (40 g/day nano-encapsulated PE from OL); and T2 (400 g/day olive leaf pellets plus 30 g/day micro-encapsulated PE from OMWW) for 40 days. Final body weight and carcass yield were unaffected, although the average daily gain was higher in T2 (p < 0.05). Meat from T2 exhibited lower moisture and higher protein content (p < 0.01) compared with the other groups. T1 showed higher α-tocopherol levels (p < 0.05). Lipid oxidation was reduced in both treated groups (p < 0.01). Monounsaturated fatty acids tended to decrease in treated groups (p = 0.057), while saturated and polyunsaturated fatty acids (PUFA) were unaffected. However, T2 showed higher total n-3 PUFA (p < 0.05), and a more favourable n-6/n-3 ratio (p < 0.01) was found in treated groups. These results highlight the potential of olive–derived polyphenols as functional feed ingredients to enhance meat quality and promote sustainable, circular livestock systems.