A large amount of CdS‐loaded composite UiO‐66‐(SH)2−CdS (104 wt %) was obtained by using a thiol‐functionalized UiO‐66‐(SH)2 through a well‐designed, two‐step, solid‐solution doping method. The thiol groups on the Metal‐Organic Framework couple with the cubic CdS nanoparticles to uniformly distribute over the UiO‐66‐(SH)2. A series of UiO‐66‐(SH)2−CdS‐x (0.4400 nm), a high quantum efficiency, 25.8 %, at 420 nm and a perfect stability, which retained photocatalytic activity even after the catalyst had been soaked in boiling water for 24 h. [ABSTRACT FROM AUTHOR]