As an emerging high-entropy energy harvesting technology, triboelectric nanogenerators (TENGs) have received extensive research attention, and have expanded the application range in the era of Internet intelligence by rationally engineering triboelectric materials. In this report, we present a simple approach to fabricate magnetic TENGs (M-TENGs) based on composite films of carboxylated chitosan. The composite film has good biocompatibility and its saturation magnetization increases with the increase of the concentration of magnetic nanoparticles, to a maximum value of 29.4 emu/g. The M-TENG exhibited the maximum open-circuit voltage and short-circuit current of 168.2 V and 7.6 μA, respectively, with a maximum output power density of 107.5 mW·m−2. It can drive LED lights and small commercial electronic components. In addition, the assembled flexible M-TENG can be used as a self-powered human motion monitoring sensor with stable and sensitive response to continuous motion, which is a good candidate for monitoring human daily and clinical motion. Meanwhile, it is used as a sensor for real-time monitoring and protection of cultural relics by utilizing its magnetic properties and sensitivity, thus widening its application in preventing historical relics with cultural value from damages.