Chemical warfare agents (CWAs) such as sarin are still available and their toxicity is a real danger. This study aims at investigating the ability of heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (M-β-CD) to trap and decontaminate sarin by a host–guest inclusion complex. The binding mechanism of the interactions between sarin and M-β-CD was described by a quantum mechanical (QM) framework combined with methods such as QTAIM, NBO, and also molecular electrostatic potential (MESP). Furthermore, molecular dynamics (MD) simulations were conducted to determine the dynamical behavior, molecular structure, and binding affinities of the inclusion complex. A special procedure for encapsulating sarin into the M-β-CD cavity was employed, which includes three stages: annealing, equilibrium, and production. It was shown how the interactions of glycosidic oxygens of the M-β-CD with phosphorus can help to liberate fluorine and hydrolyze sarin. Also, the dynamic and structural parameters revealed that intermolecular hydrogen bonds and van der Waals interactions effectively ensured the penetration and surrounding of sarin into the cavity by the host molecule. This study shows considerable potential for future use to design β-CD derivatives that are able to trap and degrade CWAs.