Abstract: Photochromism refers to a reversible chemical reaction in which a compound undergoes structural changes under specific light irradiation. Photochromic molecules based on such reactions have attracted significant attention in fields such as materials science, biology, and medicine. In recent years, visible-light photochromic dyes have emerged as a research hotspot in this area due to their low biological toxicity and strong tissue penetration capabilities. In this work, a novel "vinylene-bridged side-chain fusion" strategy is adopted to construct 6π electrocyclization photochromic units using perylenetetracarboxylic ester dyes, which are an inexpensive, readily modifiable class of chromophores with extended π-conjugated backbones. Computational results indicate that the photochromic molecules preferentially adopt an anti-parallel conformation, with their lowest unoccupied molecular orbitals (LUMOs) fully delocalized across the thiophene reactive carbons. This electronic structure, in line with the Woodward–Hoffmann rules, ensures efficient photoresponsiveness at the maximal absorption wavelength. The target compounds undergo rapid ring-closing reactions upon irradiation with blue light (475 nm), efficiently switching to the closed-ring state, and subsequently revert to their initial open-ring configuration under near-infrared light (730 nm), demonstrating robust, reversible photochromic behavior. The polarity of the solvent has a significant effect on the efficiency of the ring-closing reaction and the stability of the closed form, but has little influence on the ring-opening process. Moreover, extending the conjugation on the side chain effectively red-shifts the absorption wavelength of the closed form and meanwhile enhances its thermal stability. These new long-wavelength responsive photochromic dyes show promising potential for application in emerging interdisciplinary fields such as photodynamic therapy and photopharmacology.