In this work, a silver-capsuled composite particle at micro-size has been facilely developed for electrostatic patterning of copper layers on flexible substrates, with high performance across manufacturing scalability, printing resolution and speed, and production affordability to end users. Herein, we launched a capping method for designing the particle as decorated with PVP capped silver ion as catalytic precursor all in one wet environment, in which the catalytic ion is successfully reduced and uniformly distributed when mixed with the primary particle. In further combination with an air plasma treatment on the surface of a flexible polyimide film, the toner particle can be successfully electrostatically developed and fused onto the substrates with retained lateral printing quality. We disclose a process of passing the patterned substrates through a gentle exposure to a sulfur acid solution for promoting electroless deposition of copper layer. The obtained copper tracks have electrical conductivity of ∼10−Ω cm with controllable thickness up to about 40 μm, which is feasible for applications in wearable electronics, embedded systems, and implanted biomedical devices.