Viologen has attracted much attention due to its sensitive chromic properties in response to external stimuli, especially its photochromic behavior. Herein, a viologen derivative, 4PV•2Br, was prepared based on our previous studies, which exhibited strong photoluminescence due to the introduction of the thiazolothiazole group but was silent to light, even under 300 W UV light irradiation. By anion exchange with tetraphenylborate, a new viologen derivative, 4PV•2B(Ph) 4 , was obtained, which not only exhibits strong fluorescence with a quantum yield of 69% and a lifetime of 1.93 ns in solution but also exhibits sensitive photochromism to UV light, even under sunlight within 5 s. It is very sensitive to light and may become a potential excellent solar chromic material. It should be emphasized that the colored 4PV•2B(Ph) 4 radical is particularly stable and can maintain its coloring state in air for a long time, while vinegar vapor can cause it to fade in 2 s, giving it good color reversibility. The single-crystal structure before and after UV light excitation shows that UV light shortens the π•••π distances between B(Ph) 4 anions and 4PV cations, which is beneficial to faster electron transfer between them and the formation of stable viologen radicals. Sensitive photochromism accompanied by strong photoluminescence may endow 4PV•2B(Ph) 4 with potential application in information security and provide a good strategy to regulate the functionality of materials by regulating the counteranions of new viologen derivatives.