Cucurbit[n]urils (Q[n]s) are essential members of the supramolecular organic framework family owing to their distinct structure. In this study, Q[8] was employed as a building block and a Q[8]-based porous supramolecular assembly (Q[8]–PSA) was prepared by simple crystallization in an aqueous HCl solution. This Q[8]–PSA was constructed through the outer surface interaction of Q[8] and hydrogen bonding between the lattice water molecules and portal carbonyl oxygens of Q[8]. Q[8]–PSA provides a uniform pore structure, large specific surface area, and uniform pore size, which was characterized by single crystal XRD, TEM, SEM, and FT-IR spectroscopy. Following this, the obtained Q[8]–PSA was employed to evaluate its adsorption property towards 8 drugs with varying shape and size. Moreover, the controlled release of drugs from Q[8]–PSA was also investigated at pH 4.5 and 6.8 using an orbital oscillator.