A ligand-free, palladium-catalyzed amidocarbonylation reaction of aromatic aldehyde, acetamide, and CO in ionic liquids [C4mim]PF6, [C6mim]PF6, [C8mim]PF6, and [C6mim]BF4 as solvents is developed. The yields decreased in the order [C6mim]PF6 > [C8mim]PF6 > [C4mim]PF6 > [C6mim]BF4, and substrate concentration affected the catalytic activity of amidocarbonylation. The excellent yield with up to 98% in amidocarbonylation of benzaldehyde was obtained using 15 mol% LiBr · H2O and 6 mol% H2SO4 at 80 °C. This reaction could proceed smoothly, resulting in several functionalized ortho-, meta-, and para-substituted N-acyl-α-phenylglycines in moderate to good yields, and o-tolualdehyde and m-tolualdehyde as substrates were amidocarbonylated for the first time in [C6mim]PF6. A significant dependence of product yield on both substituent position and electronic effect of aromatic aldehyde was observed. The ligand-free synthetic method and convenient separation of the products highlighted the versatility of this newly developed methodology.