In view of immense importance of silylenes and the fact that their properties undergo significant changes on substitution with halogens, here, we have used B3LYP/6‐311++G** level of theory to access the effects of 1–4 halogens (X = F, Cl, Br, and I) on four unprecedented sets of cyclopentasilylene‐2,4‐dienes; with the following formulas: SiC₄H₃X (1 _X), SiC₄H₂X₂ (2 _X), SiC₄HX₃ (3 _X), and SiC₄X₄ (4 _X). In going down from F to I, the singlet (s)‐triplet (t) energy gap (ΔE_s‐t, a possible indication of stability), and band gap (ΔE_H‐L) decrease while nucleophilicity (N), chemical potential (μ), and proton affinity (PA) increase. The overall order of N, μ, and PA for each X is 2 _X > 1 _X > 3 _X > 4 _X. Precedence of 2 _X over 1 _X is attributed to the symmetric cross conjugation in the former. The highest and lowest N are shown by 2 _I and 4 _F. The trend of divalent angle () for each X is 4 _X > 1 _X > 3 _X > 2 _X. The results show that in going from electron withdrawing groups (EWGs) to electron donating groups (EDGs), the ΔE_s‐t and ΔE_H‐L decrease while N, μ, and PA increase. Also, rather high N of our scrutinized silylenes may suggest new promising ligands in organometallic chemistry.