Macrophage activation plays a central role in neoatherosclerosis and in-stent restenosis after percutaneous coronary intervention (PCI). Galectin-3, mainly expressed on macrophages, is an important regulator of inflammation. This study aimed to investigate the effects of berberine (BBR) on oxidized low-density lipoprotein (ox-LDL)-induced macrophage activation and galectin-3 expression and their underlying mechanisms. THP-1-derived macrophages were pretreated with BBR prior to stimulation with ox-LDL. Galectin-3 expression was measured by real-time PCR, Western blotting, and confocal microscopy. Macrophage activation was assessed by lipid accumulation, expression of inflammatory cytokines, and CD11b and CD86. Plasma galectin-3 levels were measured in patients undergoing PCI at baseline and after BBR treatment for 3 months. BBR suppressed ox-LDL-induced upregulation of galectin-3 and macrophage activation. Overexpression of galectin-3 intervened the inhibitory effect of BBR on macrophage activation. BBR activated phospho-AMPK and inhibited phospho-NF-κB p65 nuclear translocation. AMPK inhibition and NF-κB activation abolished the inhibitory effects of BBR on galectin-3 expression and macrophage activation. Combination of BBR and rosuvastatin exerted greater effects than BBR or rosuvastatin alone. However, BBR treatment did not further reduce plasma galectin-3 after PCI in patients receiving standard therapy. In conclusion, BBR alleviates ox-LDL-induced macrophage activation by downregulating galectin-3 via the NF-κB and AMPK signaling pathways.