Triboelectric nanogenerators (TENGs) are promising candidates for self-powered sensors or power supplies, with advantages of low production cost and facile fabrication. The electrical output performance of TENGs can be enhanced by increasing the effective contact area between triboelectric materials. However, typical methodologies to improve surface roughness, including photolithography, commonly suffer from high processing cost and limited selection of materials. Herein, a TENG with complementary nanopatterns (CN-TENG), synergistically composed of protruded metals (gold) and indented polymers (Teflon), is fabricated by means of block copolymer (BCP) self-assembly, while adjusting the molecular weight (MW) of the BCPs. Mussel-inspired polydopamine treatment was applied to optimize the interfacial energy of the chemically inert triboelectric material surfaces for desirable BCP nanopatterning. The resultant nanopatterned pairs were systematically classified into nine types of combinations to exploit the interplay among different patterned morphologies. The CN-TENG yielded substantially improved electrical outputs compared to the nonpatterned counterpart and a spatially designed array consisting of six CN-TENGs was successfully utilized for a gait monitoring system to detect gait abnormalities.