On-surface chemistry is a powerful method to fabricate organic nanostructures with high precision onto different kinds of surfaces. On more inert surfaces, the lack of reactivity of the underlying substrate can be circumvented by using the electrons from a scanning tunneling microscope (STM) tip, as a stimulus, to produce the reactants of a targeted reaction. Here, another role of the STM tip is exploited in the fabrication of organic nanostructures. The STM tip is first used as a source of stimulating electrons to generate organic radicals on a Si(111)√3x√3R30°-B surface. Then, the STM tip acts as a conveyor to transfer radicals among different interfaces, for finally creating new hybrid organic−inorganic interfaces. Our approach enables new alternatives to initiate, control, and provide radicals into oligomerization reactions with tunneling electrons and to fabricate nanostructures with a molecular precision.