The on-surface Heck reaction of aryl bromides with terminal alkene has been achieved for the first time. With palladium as the catalyst, cross-coupling of porphyrin-derived aryl bromides with terminal alkene proceeds with high selectivity on an Au(111) surface, as determined by scanning tunneling microscopy at the single molecular level. Density functional theory calculations suggest that the on-surface Heck reaction proceeds via debromination of aryl bromide, addition to the C═C bond, and elimination of hydrogen, ultimately affording the cross-coupling product.