Doxorubicin (DOX) is a wide spectrum antitumor drug. However, its clinical application is limited due to the cardiotoxicity. Carvedilol (CAR) is a β-blocker used to treat high blood pressure and heart failure. Accordingly, supplementation with natural antioxidants or plant extracts exerts protective effects against various injury in vivo. Carnosic acid (CAA), the principal constituent of rosemary, has various biological activities, including antioxidant, antitumor, and anti-inflammatory. Here, heart injury mouse model was established using DOX (20 mg/kg) in vivo. And cardiac muscle cell line of H9C2 was subjected to 0.5 μM of DOX for 24 h in vitro. Then, the protective effects of CAA and CAR alone, or the two in combination on DOX-induced cardiotoxicity in vivo and in vitro were explored. The results indicated that both CAA and CAR, when used alone, were moderately effective in attenuating DOX-induced cardiotoxicity. The combination of two drugs functioned synergistically to ameliorate cardiac injury caused by DOX, as evidenced by the significantly reduced collagen accumulation and improved dysfunction of heart. CAA and CAR exhibited stronger anti-oxidative role in DOX-treated mice partly by augmenting the expression and activities of the anti-oxidative enzymes. In addition, inflammatory response was significantly suppressed by the two in combination, proved by the decreased pro-inflammatory cytokines (COX2, TNF-α, IL-6, IL-1β and IL-18), which was associated with the inactivation of nuclear factor κB (NF-κB). Furthermore, DOX-stirred apoptosis and autophagy were dramatically attenuated by the co-treatments of CAA and CAR through down-regulating cleaved Caspase-3 and LC3B signaling pathways. The effects of CAA and CAR combination against cardiotoxicity were observed in H9C2 cells with DOX stimulation. Our findings above suggested that the use of CAR and CAA in combination could be expected to have synergistic efficacy and significant potential against cardiotoxicity induced by DOX.