Polymer nanocomposites with exceptionally high mechanical properties owing to strong interfacial attraction have garnered tremendous interest in the research community. In general, tough and robust polymer nanocomposites are usually obtained via dispersing a nano‐flaky filler in the polymer matrix, although the strategy is only sometimes practically viable. To this end, in this work, a facile strategy has been adopted to achieve a strong and tough polymer nanocomposite. A novel mussel‐inspired full interpenetrating polymeric network (IPN) consisting of polyvinylalcohol and polydopamine was prepared. This technique helped integrate the advantages of dopamine chemistry with forming a full IPN using Borax as a common crosslinker. The infusion of 1 wt% acid‐modified carbon nanotubes (ACNT) in the IPN matrix helped greatly improve the current state‐of‐the‐art. The synergistic effect of nano‐reinforcement and formation of ester linkage through a substantial amount of di‐diol complexation dominated and accounted for the significant enhancement of mechanical properties. This is further supported by decreased intensity of free OH groups in the FTIR investigations, viscosity enhancement from rheological behavior, and temperature‐dependent dynamic mechanical property analysis. Such an IPN structure is a promising way to enhance mechanical properties.