We describe the application of incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) for in situ measurements of atmospheric NO2 using a blue light-emitting diode. The mirror reflectivity is determined by the transmitted intensity variation through the cavity caused by Rayleigh scattering. Concentrations of atmospheric NO2 (1 to 35 ppbv) during the seven-day period are retrieved from the absorption spectra. The IBBCEAS measurement data are compared with those of a commercial long path differential optical absorption spectroscopy. The linear regression has a correlation coefficient and a slope of 0.983 and 0.975, respectively.