A closet organizer includes a shelf that has horizontal partition panels fixedly connected between two vertical side panels thereof to divide the internal space of the shelf into multiple vertically spaced receiving spaces, and -shaped, -shaped and L-shaped partition members selectively mounted in the receiving spaces to divide each receiving space into multiple compartments, and hook and loop materials respectively provided at the top and bottom sides of the horizontal partition panels and the -shaped, -shaped and L-shaped partition members for enabling the -shaped, -shaped and L-shaped partition members to be detachably secured to the two vertical side panels horizontal partition panels of the shelf.