With the rapid development of lightweight, portable, and even wearable electronics, there is an increasing demand for flexible supercapacitors with excellent electrochemical performance. Here, we present the design and preparation of a novel architecture with SnO2 dots uniformly confined on the activated porous carbon nanofibers (CNFs) using copper and its oxides as the hard templates for generating holes. Not only does the single electrode itself with a certain loading mass of SnO2 show larger specific capacitance, better rate capability, and higher conductivity than the bare CNFs and activated CNFs/SnO2 electrodes, but the assembled quasi-solid-state symmetric supercapacitor also exhibits good flexibility as well as superior electrochemical property with satisfactory energy density and favorable cycling stability, which indicates the great potential for practical applications. This work may provide a versatile and low-cost strategy to construct carbon/metal oxide nanostructures with robust binding force at the interface for adhesive-free supercapacitors.