The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variant (B.1.1.529) underwent a substantial number of alterations, and the accompanying structural mutations in the spike protein prompted questions about the virus’s propensity to evade the antibody neutralization produced by prior infection or vaccination. New mutations in SARS-CoV-2 have raised serious concerns regarding the effectiveness of drugs and vaccines against the virus; thus, identifying and developing potent antiviral medications is crucial to combat viral infections. In the present study, we conducted a detailed in silico investigation that involves molecular docking, density functional (DFT) analysis, molecular dynamics (MD) simulations, and pharmacological analysis followed by an in vitro study with the spike protein. Among fifty terpenes screened, cryptotanshinone and saikosaponin B2 were found to be potent S1-RBD spike protein inhibitors, displaying considerable hydrogen bond interactions with key binding site residues, significant binding affinity, and high reactivity attributed to band gap energy. In addition, 100 ns molecular dynamics (MD) simulations further substantiated these findings, showcasing the stability of the compounds within a biological environment. With favorable pharmacokinetic properties and a low half inhibitory concentration (IC50) of 86.06 ± 1.56 μM, cryptotanshinone inhibited S1-RBD of the SARS-CoV-2 Omicron variant. Our findings account for in-depth research on cryptotanshinone as a SARS-CoV-2 inhibitor.