The ultrasound-assisted extraction (UAE) was employed to extract geniposide from Gardenia jasminoides, and the effects of extraction temperature, extraction time, ultrasound power, solvent/sample ratio, and particle size on the concentration of geniposide were investigated. A kinetic model was proposed to describe the extraction process based on Fick’s first law and the medicinal herb extraction mechanism, and the calculated values were in good agreement with the experimental data. The results indicated that the model could be used to better comprehend the ultrasound-assisted extraction of geniposide from Gardenia jasminoides and systematically optimize the process.