A mesoscopic nitrogen-doped TiO2 sphere has been developed for a quasi-solid-state dye-sensitized solar cell [DSSC]. Compared with the undoped TiO2 sphere, the quasi-solid-state DSSC based on the nitrogen-doped TiO2 sphere shows more excellent photovoltaic performance. The photoelectrochemistry of electrodes based on nitrogen-doped and undoped TiO2 spheres was characterized with Mott-Schottky analysis, intensity modulated photocurrent spectroscopy, and electrochemical impedance spectroscopy, which indicated that both the quasi-Fermi level and the charge transport of the photoelectrode were improved after being doped with nitrogen. As a result, a photoelectric conversion efficiency of 6.01% was obtained for the quasi-solid-state DSSC.