In this review, we focus on the integrated assemblies of metal complexes and their functional emergence generated by the synergy effects of π-π stacking interaction and metal complexation. Programmable construction of integrated molecular assemblies is the best measure for bringing out the emergent functions which can be evolved from the intermolecular communications of functional molecular components. Combination of π-π stacking interaction and metal complexation allows not only to reinforce the mutual interactions but also to generate the emergent intermolecular communications. This review introduces the recent studies including the synergy effects on electrical, magnetic, catalytic and molecular recognition functions in soft, crystalline and single molecular materials.