Pd‐catalyzed 5‐exo‐trig or 6‐endo‐trig C-H oxidative cyclization of C‐homoallyl‐N‐sulfonylhydrazones to 5‐vinylpyrazolines or 6‐methylidene‐1,4,5,6‐tetrahydropyridazines, respectively, is shown to be controlled in a highly selective manner by the ionic character of the PdII catalytic center. This character is ultimately defined by the nature of the X ligand in the PdX2 salt serving as an in situ precursor of the active catalytic species involving BIPHIMIP {2‐(diphenylphosphino)‐1‐[2‐(diphenylphosphino)phenyl]‐1H‐imidazole} as an optimal spectator diphosphine ligand for both processes. Whereas acetates (X=OAc) favor the 6‐endo process, noncoordinating anions such as tosylates and triflates (X=OTs, OTf) favor the 5‐exo process.