The mechanisms of iron‐catalyzed regioselective anti‐Markovnikov addition of C‐H bonds in the aromatic ketones to alkenes are studied using Density Functional Theory (DFT) calculations with the B3LYP‐D3 method. Our results show that the overall catalytic cycle includes the initial generation of aromatic ketone C‐H activation, the coordination and insertion of a styrene, and finally C‐C reductive elimination. Two different alkylation products are obtained through the linear or branched formation via several different paths. The formation of the linear product is energetically favorable over that of the branched product, which is in agreement with the experimental observation. The rate‐limiting step for the whole catalytic cycle to obtain the main linear product is the reductive elimination step where the Gibbs free energy in solvent THF ΔGsol is 13.5 kcal/mol computed using the SMD method. The mechanisms of iron‐catalyzed regioselective anti‐Markovnikov addition of CH bonds in the aromatic ketones to alkenes were studied using DFT (B3LYP‐D3) calculations. The results show that the rate‐limiting step for the whole catalytic cycle to obtain the main linear product is the reductive elimination step where the Gibbs free energy in solvent THF, ΔGsol is 13.5 kcal/mol.