Nanometer scale lateral heterostructures with atomically sharp band discontinuities can be conceived as the 2D analogues of vertical Van der Waals heterostructures, where pristine properties of each component coexist with interfacial phenomena that result in a variety of exotic quantum phenomena. However, despite considerable advances in the fabrication of lateral heterostructures, controlling their covalent interfaces and band discontinuities with atomic precision, scaling down components and producing periodic, lattice‐coherent superlattices still represent major challenges. Here, a synthetic strategy to fabricate nanometer scale, coherent lateral superlattice heterojunctions with atomically sharp band discontinuity is reported. By merging interdigitated arrays of different types of graphene nanoribbons by means of a novel on‐surface reaction, superlattices of 1D, and chemically heterogeneous nanoporous junctions are obtained. The latter host subnanometer quantum dipoles and tunneling in‐gap states, altogether expected to promote interfacial phenomena such as interribbon excitons or selective photocatalysis. A 2D lateral superlattice heterostructure with unprecedented single‐bond band discontinuities and heterocomponent dimensions down to one nanometer is realized by the coupling of interdigitated nanoribbons into a nitrogen‐doped nanoporous graphene structure. The atomic scale band discontinuities at the nanoporous heterojunctions endow this nanomaterial with a multifunctionality that can be relevant for photodetection, excitonic solar cells, water splitting, or selective nanosieving.