The antibiotic treatment of periprosthetic joint infections (PJI) is complicated by the presence of biofilm produced by bacteria on the abiotic surface of the implant. Bacteria within the deeper layers of the biofilm become metabolically less active, resulting in antibiotic tolerance due to several mechanisms. This review describes the basic principles of antibiotic treatment in PJI in relation to the behavior of bacteria within the biofilm. The concept of biofilm-active antibiotics will be explained from an in vitro as well as in vivo perspective. Evidence from clinical studies on biofilm-active antibiotics in PJI will be highlighted, mainly focusing on the role of rifampicin for Gram-positive microorganisms and fluoroquinolones for Gram-negative microorganisms. The optimal treatment duration will be discussed as the timing of switching to oral antibiotic therapy.