In this work, we have performed a computational study using the B3LYP/6‐31G(d,p) density functional theory (DFT) method of the solvent effects, the mechanism and the selectivity of the cationic imino‐Diels–Alder cycloaddition reaction between in situ‐generated cationic 2‐azadienes and arylpropenes. This reaction proceeds via a stepwise mechanism, in which the first step is the rate determining, favouring kinetically and thermodynamically the formation of the cycloadduct generated from meta‐exo approach. Analysis of different solvent effects indicates that the low polar solvents are the best solvents for this kind of reaction. The global reactivity descriptors indicates that the dienimine 1 is a strong electrophile, whereas, ethylene 2 is a good nucleophile. The local reactivity descriptors explain the obtained experimental meta regioselectivity. The NCI analysis indicates the presence of different favourable non‐covalent interactions, while QTAIM analysis indicates that steric hindrance at the meta‐endo approach is the origin for the experimentally observed meta‐exo stereoselectivity. The obtained results are in agreement with the experimental data.