Four new chromenones, kielmeyerones A-D (<b>1</b>-<b>4</b>), were obtained from the roots of <i>Kielmeyera reticulata</i>. Their structures were elucidated based on spectroscopic data (NMR and HRESIMS) interpretation. The pharmacological activity of kielmeyerone A (<b>1</b>), the major compound, was evaluated using in vitro and in vivo inflammation and pain models. During in vitro screening, <b>1</b>, at noncytotoxic concentrations (0.097-1.56 μM), inhibited NO production by J774 macrophages stimulated with LPS and IFN-γ. In the complete Freund's adjuvant-induced inflammation model in mice, <b>1</b> (12.5-50 mg/kg) inhibited paw edema, demonstrating an anti-inflammatory effect. Additionally, <b>1</b> (12.5-50 mg/kg) induced a dose-dependent antinociceptive effect in the late phase of the formalin test, a profile similar to those of nonsteroidal anti-inflammatory drugs. Mice treated with <b>1</b> (100 mg/kg) did not show motor performance alterations using a rota-rod test. Thus, the present study has characterized new chromenones from <i>Kielmeyera reticulata</i> and has provided evidence of the anti-inflammatory and antinociceptive properties of one of these, kielmeyerone A (<b>1</b>).