Psoriasis is a chronic immune mediated disease in which the interplay of T cells and keratinocytes seems to play a key role. In this context, the interleukin (IL)-23/IL-17 axis is currently considered to be crucial in the pathogenesis of psoriasis and the selective inhibition of IL-23 may be viewed as an improvement of treatments blocking both IL-23 and IL-12, since its upstream actions. Areas covered: The authors performed a thorough and updated review on guselkumab, a fully human IgG1λ monoclonal antibody that blocks the p19 subunit of IL-23, analyzing efficacy and safety data from phase I, II and III trials. Expert opinion: Guselkumab represents a very promising therapy, providing an alternative mechanism of action with high efficacy and safety profiles, sustained total skin clearance, and rapid onset of effect also to psoriasis patients who previously failed or experienced an inadequate response to anti-TNF-α or anti-IL12/23. Guselkumab will definitively shift therapeutic goals of psoriasis management from PASI 75 to PASI 90 and 100 due to its exciting trials results, also favored by its increased treatment adherence due to its administering regimen (100 mg injection at week 0, 4 and then every 8 weeks).