Display omitted •Active 1T-MoS2 nanosheets are covalently functionalized with n-butyl chains (~4%).•Introduction of n-butyl chains increased the interlayer spacing to 13.8 Å from ~9 Å.•Functionalization and solvent enrichment process improved the stability of 1T-MoS2.•en-Bu-1T-MoS2 showed superior performance in clean energy (HER & DSSC) applications. The selective enrichment of a highly active form/phase of material is essential for the development of potential candidates for specific applications. Herein, we demonstrate the first example of the covalent functionalization of a highly active 1T phase of outstanding 2D material, such as MoS2, and its enrichment (>94%) using a solvent extraction technique. Covalent functionalization stabilizes the metastable 1T phase with increased interlayer distance, which makes it a more suitable candidate for energy applications. The enriched functionalized 1T-MoS2 with n-butyl groups (en-Bu-1T-MoS2) shows a lower overpotential of 169 mV (vs. Reversible Hydrogen Electrode, RHE) with the loading mass of 0.9 mg cm−2 toward the hydrogen evolution reaction (HER). The continuous HER of en-Bu-1T-MoS2-based electrode for >200 h showed only <11% increment in the overpotential of HER, which suggests the ultra-long term stability of en-Bu-1T-MoS2 compared to the covalently functionalized 1T-MoS2-based HER electrocatalysts reported thus far. Interestingly, the semi-transparent en-Bu-1T-MoS2 film also served as an excellent counter electrode for dye-sensitized solar cells (DSSCs) with the higher power conversion efficiency (PCE) of 9.11% and 82% of PCE retention even after 200 h. The unprecedented method presented in this work is a unique example, which shows the possibility of improving material properties with the help of a novel approach.