Abemaciclib, a cyclin–dependent kinase 4/6 (CDK4/6) inhibitor, shows promising antitumor activity in estrogen receptor–positive (ER+) breast cancer cells. This study was conducted to sightsee the interaction mechanism between the newly licensed anti–breast cancer drug abemaciclib and bovine serum albumin (BSA) via a spectral and computational analysis approach. The spectroscopy studies were purposed to realize the characteristics, structural changes, and thermodynamic parameters at different temperatures related to the binding interactions. Upon the addition of the abemaciclib drug into BSA (1,0 → 1:7; BSA:abemaciclib), the intensity of BSA was remarkably quenched through a static quenching mode. The values of the binding site (n) were equal to ∼1, approximated to only one binding site on the BSA, which showed that a robust static complex could be formed with a quantity ratio of 1:1. Studies on the measurement of particle size, circular dichroism, and infrared spectroscopy were also performed, and the results were successfully confirmed by molecular docking studies. The molecular docking study has been demonstrated to be both highly effective and dependable in establishing the forces that control the binding stability of the abemaciclib−BSA complex by both hydrogen bonding and hydrophobic interactions. The results thus provide valuable information for the changes in structural and pharmacokinetic characteristics between the abemaciclib drug and BSA.