The ability to control molecular structure and properties through external stimuli opens avenues for the design and development of advanced materials for applications involving organic electronics, sensing, biomedical research, molecular machines, and energy storage. In this context, indigoid photoswitches such as 3-or 2-oxindole derivatives (Fig. ), represent an intriguing class of molecules, characterized by their reversible photoisomerization and tunable electronic structures. Oxindole/indolone derivatives (3oxindole called oxindoles or 2-oxindole derivatives named azaaurones or hemiindigos) are typically synthesized via the Knoevenagel reaction, which involves a condensation of an aldehyde, or ketone with the respective active hydrogen compounds to form a car boncarbon double bond (Fig. ). Traditionally, the Knoevenagel reaction is conducted in solution under homogeneous conditions. However, the need for environmentally friendly synthetic processes has spurred exploration into alternative methods. In this context, mechanochemistry is a green and sustainable technique that not only minimizes waste generation but also offers unique reaction pathways and selectivity profiles, inaccessible through conventional solution-based methods. In 2003, the first reports of aldol elimination reactions under mechanochemical conditions appeared. Those reactions used minerals (calcite or fluorite) , CaO, or triethylbenzylammonium chloride as catalysts and bases, or even proceeded without any catalysts. Mechanochemistry has demonstrated remarkable promise in the synthesis of azobenzenes, aurones, merocyanine photoswitches and their modifications; as well as in the synthesis of macrocycles. However, to our knowledge, the mechanochemical synthesis of indigoid photoswitches has not been reported. In this study, we demonstrate that the solvent-free mechanochemical procedure of the Knoevenagel reaction yields hemiindigos, hemithioindigos, and oxindoles in high yields, requires short reaction times, and tolerates a wide scope of reagents. The reaction is selective in regards to the double-bond stereochemistry and allows for stereoselective synthesis of multichromophoric and complex macrocyclic derivatives. The photophysical properties of selected new products are also reported.