Emulsions are widely used in numerous fields. Therefore, there has been increasing interest in the development of new emulsification strategies toward emulsions with advanced functions. Herein we report the formation of diverse emulsions by host-guest interaction-mediated interfacial self-assembly under mild conditions. In this strategy, a hydrophilic diblock copolymer with one block containing β-cyclodextrin (β-CD) can assemble at the oil/water interface when its aqueous solution is mixed with an oil phase of benzyl alcohol (BA), by host-guest interactions between β-CD and BA. This results in significantly reduced interfacial tension and the formation of switchable emulsions with easily tunable droplet sizes. Furthermore, nanoemulsions with excellent stability are successfully prepared simply via vortexing. The self-assembled oil-in-water emulsions also show catastrophic phase inversion, which can generate stable bicontinuous phase and water-in-oil emulsions, thereby further extending phase structures that can be realized by this host-guest self-assembly approach. Moreover, the host-guest nanoemulsions are able to engineer different nanoparticles and microstructures as well as solubilize a diverse array of hydrophobic drugs and dramatically enhance their oral bioavailability. The host-guest self-assembly emulsification is facile, energetically friendly, and fully translatable to industry, therefore representing a conceptually creative approach toward advanced emulsions.