Our previous study showed that micelle silymarin (MS) improved the antioxidant capacity of lactating sows and average daily gain of fattening pigs; however, its effect on weaned piglets has not yet been elucidated. The present work aimed to explore the influence of varying doses of MS on growth performance, blood profiles, nutrient digestibility, and antioxidant capacity of weaned piglets. One hundred and twenty weaned piglets (60 males and 60 females) at the age of 21 days (average body weight = 6.50 kg) were randomly divided into 3 dietary groups. Each treatment consisted of 8 replicate pens (5 pigs/pen). The following feeds were applied: a basal diet (without MS) and a basal diet with the addition of 0.05% MS or 0.1% MS. The feeding trial lasted 42 days. The results demonstrated that dietary MS linearly increased average daily gain over the entire period (P = 0.011). Average daily feed gain tended to be higher with increasing MS doses in the diet (P = 0.058). Faecal score and nutrient utilisation in terms of dry matter, nitrogen, and gross energy were not affected by MS doses (P > 0.05). On day 42, serum immunoglobulin M levels were elevated after the inclusion of both 0.05% and 0.1% MS in the diet (P = 0.016). Additionally, malondialdehyde levels showed a linear reduction on days 14 and 21 (P = 0.005), while glutathione levels were increased on day 21 (P = 0.005). In summary, supplementing the diet of weaning piglets with MS had no adverse effects on their health. Furthermore, including 0.1% MS in the diet of weaned piglets tended to improve growth performance and antioxidant capacity.