A hemostatic adhesive hydrogel with multifunctional properties is required for surgical sealants. Herein, we engineered a mechanically robust nanocomposite hydrogel with significant adhesion strength and blood clotting. This nanocomposite hydrogel compromised of thiolated gelatin (Gel-SH) and gelatin methacrylate (GelMA) to support cell viability and proliferation and polydopamine functionalized Laponite? (PD-LAP) to promote mechanical properties, adhesion strength and blood clotting. Nanocomposite hydrogels were formed via three chemical interactions of Michael reaction between Gel-SH and GelMA, photo-crosslinking of GelMA and covalent interaction between PD-LAP and hydrogel structure. Results revealed that the swelling ratio, biodegradability, and mechanical properties of nanocomposite hydrogels were significantly controlled by adjusting the concentration of PD-LAP. For instance, nanocomposite hydrogels exhibited tensile and compressive strength in the range of 22-84 kPa and 54-153 kPa, respectively, depending on the PD-LAP content. Furthermore, nanocomposite hydrogels revealed great recovery ability, strong tissue adhesiveness and significantly less blood clotting time than Gel-SH/GelMA hydrogel (2.25 min). Our results indicated that nanocomposite hydrogels were cytocompatible and supported the viability of proliferation of L929 cells. The simplicity, low cost, tunable mechanical properties, excellent blood clotting time, and cytocompatibility of the hydrogel comprised of Gel-SH, GelMA, and PD-LAP highlight its potential for hemostat sealants.