Anion−π+ interaction has gained continuous attention in diverse organic aggregates, which can effectively alter the emission behavior. Herein, the anion−π+ interaction is introduced to the phosphonium salts which exhibit tunable thermally activated delayed fluorescence and phosphorescence emission. Intriguingly, the emission spectra evolve from deep blue to yellow emission by regulating the anion−π+ interaction strengths through varying the anions such as BF4-, CF3SO3-, PF6-, and NO3-, accompanied by adjustable luminescent decay times from milliseconds to several seconds. Notably, bright blue emission with a high photoluminescence quantum yield near 100% is achieved when substituting the iodide ions with larger counter anions. The phosphonium iodide with strong anion−π+ interaction and heavy atom effect shows a high inter-system cross rate, which inhibits the direct prompt fluorescence emission. The anion−π+ interaction and twisted structure strongly suppress the π−π stacking and afford the ultra-high photoluminescence yields. Furthermore, the participation of polar solvent molecules results in the solvation and bathochromic-shift phenomenon of the solid-state phosphonium iodide due to the ionic polarized host−guest structure. This work would provide new insights into the anion−π+ interaction in luminescent phosphonium aggregates.