Reineckea carnea (Andrews) Kunth (RCK) is known for its anti-inflammatory and antioxidant effects. But, its effects and underlying mechanisms on chronic obstructive pulmonary disease (COPD) are not well understood. This study aimed to evaluate the effects of RCK on COPD and to elucidate the mechanisms by which it modulates gut microbiota. A COPD mouse model was established through exposure to cigarette smoke (CS). Mice were then treated with oral administration of RCK aqueous extract. The anti-inflammatory effects and efficacy of RCK aqueous extract on COPD, as well as changes in microbiota composition, were evaluated. RCK aqueous extract ameliorated gut dysbiosis in CS-induced COPD mice by increasing the abundance of beneficial bacterial phyla and reducing the proliferation of pathogenic bacteria. Importantly, RCK treatment inhibited the expression of inflammatory mediators, such as IL-6, IL-8, and TNF-α at both mRNA levels and protein levels, attenuated oxidative stress in vivo in mice, and suppressed CS-induced activation of the NF-κB signaling pathway, thereby attenuating lung inflammation and restoring lung tissue structure. In conclusion, the beneficial effects of RCK aqueous extract on CS-induced COPD may be attributed to its anti-inflammatory and antioxidant properties as well as its ability to modulate gut microbial composition.