Density functional theory (DFT) calculations are used to thoroughly examine the reactivity and electronic sensitivity of pristine and BN-doped graphyne (BNG) toward nitrogen mustard (NM). Graphyne’s electrical conductivity is unaffected by the weak adsorption of NM, which occurs via the Cl atom on the material with an adsorption energy of roughly −3.1 kcal.mol−1. In addition to decreasing graphyne’s reactivity and work function, substituting isoelectronic BN linkages for CC linkages enhances the HOMO-LUMO energy gap (Eg). BNG’s electrical conductivity increases when Eg drops from 2.99 to 1.82 eV due to the adsorption of NM. Additionally, a significant change in BNG’s work function results in a variation in the field electron emission current. Lastly, it is anticipated that the desorption of NM from the BNG surface will take a brief recovery time of roughly 0.05 s at room temperature. It has also been demonstrated that NM concentration affects changes in electrical conductivity. The findings also suggest that BNG could be a promising NM sensor.