Abstract Societal well-being depends on solving biological challenges and on the development of new smart and responsive materials for new technologies. Supramolecular chemistry can provide new opportunities and solutions to these challenges and endeavors. Macrocycles are important building blocks for a myriad of supramolecular systems and are essential components of host–guest systems. Pillararenes, introduced by Ogoshi et al. in 2008, are regarded as the fifth generation of macrocycles. Pillar[n]arenes have been the focus of much attention by the scientific community in the last decade and have triggered the preparation of new families of macrocyclic arenes. In this review, on the centennial anniversary of the Bulletin of the Chemical Society of Japan, we chose to present some of our contributions to the field of pillar[n]arene chemistry and use them to review, through selected examples owing to space limitations, the applications of pillararenes in two key areas of modern biomedicine, namely improved diagnostics and better treatments. We focus on the use of cationic pillararenes as antibiofilm and antimicrobial agents and on the development of bioimaging systems based on pillararenes. We finish with a brief discussion of the achievements reached in these two fields, the unmet challenges, and future directions.