The organic donors and metal acceptors used in coordination-driven self-assembly schemes for the formation of metallomacrocycles are readily modified to deliver final architectures containing two or more functional sites. A given structure can be converted to a functional variant either by incorporating a target moiety directly into the edge or vertex building blocks or by using well-established coupling chemistry to install pendant groups. These pendant groups may be oriented outward from the metallomacrocycle core (exo), or inward into the internal cavity of the structure (endo). The modular nature of direction bonding and the self-assembly process enable a broad mix of mono- and multifunctional structures since either the donor, acceptor, or combinations of both may be functionalized within a given structure. Most examples of functionalization involve the installation of photophysically or electrochemically active groups. The resulting metallomacrocycles typically remain soluble and may be studied using traditional small-molecule characterization techniques. Functionalization also provides a way to control post-self-assembly chemistry, spanning host–guest interactions, hierarchical self-assembly schemes, and catalysis.