A ligand-free Heck–Mizoroki reaction with 5-trifluoromethanesulfonates of pyrazoles in high yield under mild conditions is described. The reaction conditions have been established through extensive studies on the palladium catalyst system (palladium sources, ligands, additives, base, and solvents) by considering how to avoid the Michael adduct of acrylic ester at the 4-position of the substrate pyrazole. The optimum conditions (palladium(II) chloride, lithium chloride, and triethylamine in N,N-dimethylacetamide) have provided various types of Heck products as 1,3,5-substituted pyrazoles.