A series of novel osmaindenes 1–6 bearing different substituents (CF3, H, I, Br, OCH3, N(Ph)2) has been synthesized by nucleophilic reaction of water with the corresponding aromatic osmanaphthalyne complexes. All osmaindenes 1–6 have been characterized by elemental analysis (EA) and nuclear magnetic resonance (NMR) spectroscopy, although the low solubilities of 3 and 4 precluded the accumulation of their 13C NMR spectra. Osmaindenes 2, 3 and 5 have also been characterized by single‐crystal X‐ray diffraction analysis. Subsequently, through solid‐state fluorescence spectroscopy, mechanochromic studies, and powder X‐ray diffraction (XRD) analysis, we found that osmaindenes 1–6 fluoresce at wavelengths in the range 500–800 nm, while also displaying reversible mechanochromic properties. The solid‐state fluorescence emission of 1 after grinding extends into the near‐infrared region. This research provides new insight into the design and synthesis of metallic materials with excellent mechanochromic properties.