A bicycle helmet packaging box includes a box body including a top wall, a bottom wall and a peripheral wall connected between the top wall and the bottom wall, and an accommodation chamber surrounded by the peripheral wall for accommodating a bicycle helmet in an upright position with a top portion thereof facing toward the top wall. The box body defines an imaginary axis that extends substantially perpendicular to the top wall and the bottom wall. The peripheral wall includes a door panel turnable about the imaginary axis. The box body has a side opening selectively closable by the door panel and adapted for the passing of the bicycle helmet to access to the accommodation chamber. The user can conveniently take the bicycle helmet out of the bicycle helmet packaging box, or put it back to the inside of the bicycle helmet packaging box.