We describe a high sensitivity and high spectral resolution laser absorption spectrometer based upon the frequency-stabilized cavity ring-down spectroscopy (FS-CRDS) technique. We used the Pound-Drever-Hall (PDH) method to lock the probe laser to the high-finesse ring-down cavity. We show that the concomitant narrowing of the probe laser line width leads to dramatically increased ring-down event acquisition rates (up to 14.3 kHz), improved spectrum signal-to-noise ratios for weak O2 absorption spectra at λ = 687 nm and substantial increase in spectrum acquisition rates compared to implementations of FS-CRDS that do not incorporate high-bandwidth locking techniques. The minimum detectable absorption coefficient and the noise-equivalent absorption coefficient for the spectrometer are about \documentclass[12pt]{minimal}\begin{document}$2\times 10^{-10}\ \rm {cm}^{-1}$\end{document}2×10−10 cm −1 and \documentclass[12pt]{minimal}\begin{document}$7.5\times 10^{-11}\ \rm {cm}^{-1}\rm {Hz}^{-1/2}$\end{document}7.5×10−11 cm −1 Hz −1/2, respectively.