PolyHIPEs are porous polymers synthesized within high internal phase emulsions (HIPEs). Recent research has shown that the locus of conventional free radical initiation (at the oil-water interface or in the organic phase) can affect the polyHIPE's structure and properties. This paper is the first investigation of polyHIPE synthesis using activators generated by electron transfer for atom-transfer radical polymerization (AGET ATRP). Two different types of initiators (organic-phase-based and nanoparticle-based) were used to synthesize polyHIPEs within both surfactant-stabilized HIPEs and nanoparticle-stabilized Pickering HIPEs. The type and locus of initiation affected the macromolecular structure for all the polyHIPEs. Furthermore, the initiator also affected both the porous structure and the wall structure of polyHIPEs synthesized within Pickering HIPEs. Depending upon the initiator, either a polyhedral void shape or a nanoparticle assembly at the interface could become "locked in" at the very beginning of the polymerization.