Recent progress in syntheses of porous carbons with designed pore architecture has rejuvenated the field of carbon chemistry and promises to provide new advanced materials. In order to reap the full benefit of designer carbons it is necessary to develop chemistries for functionalizing the porous carbon surfaces. This Review examines methods of functionalizing porous carbon through direct incorporation of heteroatoms in the carbon synthesis, surface oxidation and activation, halogenation, sulfonation, grafting, attachment of nanoparticles and surface coating with polymers. Methods of characterizing the functionalized carbon materials and applications that benefit from functionalized nanoporous carbons with designed architecture are also highlighted.