In this study, the sensing properties of the B24O24 nanocage toward the urea/creatinine molecules are presented via density functional theory (DFT) at GGA/PBE/DNP computational level. The complexes formed between urea molecules with B24O24 nanocage showed the average adsorption energy of−1.64/−1.14 and−1.55/−1.10 eV for 1:1 and 4:1 complexes in the gas phase/water medium, respectively. The corresponding values are−0.69/−0.64 and−0.61/−0.95 eV for the creatinine complexes with the desired nanocage. Adsorption of urea/creatinine molecules caused a remarkable change in the band gap (Eg) and work function (Φ) of the B24O24 nanocage in the studied complexes. Due to proper recovery time, the B24O24 nanocage is desired as a sensor for sensing the creatinine molecules. Still, it can be used as a disposable urea sensor. The considered nanocage may be applicable for urea removal due to the desirable average adsorption energy