A gold nanoparticle-based colorimetric sensor for the determination of creatinine was developed as an important index for early diagnosis of kidney function and corresponding renal diseases. Because of the unique synergistic coordination capability of adenosine and creatinine with Ag+ on a particle surface, our system exhibits an excellent selectivity to creatinine among various ions and biomolecules. There are good linear relationships of absorption changes (A(630 nm/520 nm)) over creatinine concentrations, so both calorimetric qualitative detection by the naked eye and quantitative determination by UV-vis spectrometer could be realized with an excellent limit of detection compared with that of other methods. Finally, by testing creatinine in practical samples, such as urine mimic and bovine serum, good recoveries were obtained with proper relative standard deviations.