The electronic structure of the ICl⁺ molecular ion is investigated by using high-level multireference configuration interaction (MRCI) method. To improve computational accuracy, Davidson corrections, spin-orbit coupling (SOC), and core-valence electron correlations effects are incorporated into the calculations. The potential energy curves (PECs) of 21 Λ-S states associated with the two lowest dissociation limits I⁺(¹D_g)+Cl(²P_u) and I⁺(³P_g)+Cl(²P_u) are obtained. The dipole moments (DMs) of the 21 Λ-S states of ICl⁺ are systematically studied, and the variations of DMs of the identical symmetry state (2²Σ⁺/3²Σ⁺ and 2²Π/3²Π) in the avoided crossing regions are elucidated by analyzing the dominant electronic configuration. When considering the SOC effect, the Λ-S states with the same Ω components may form new avoided crossing point, making the PECs more complex. With the help of calculated SOC matrix element, the interaction between crossing states can be elucidated. Spin-orbit coupling matrix elements involving the 2²Π, 3²Π, 1²Δ and 2²Δ states are calculated. By analyzing potential energy curves of these states and the nearby electronic states, the possible predissociation channels for 2²Π, 3²Π, 1²Δ and 2²Δ states are provided. Based on the computed PECs, the spectroscopic constants of bound Λ-S and Ω states are determined. The comparison of the spectroscopic constants between Λ-S and Ω states indicates that the SOC effect has an obvious correction to the spectroscopic properties of low-lying states. Finally, the transition properties between excited states and the ground state are studied. Based on the computed transition dipole moments and Franck-Condon factors, radiative lifetimes for the low-lying vibrational levels of excited states are evaluated. All the data presented in this paper are openly available at https://doi.org/10.57760/sciencedb.j 00213.00140.