Opportunistic Gram-negative <i>Pseudomonas aeruginosa</i> uses adhesins (e.g., LecA and LecB lectins, type VI pili and flagella) and iron to invade host cells with the formation of a biofilm, a thick barrier that protects bacteria from drugs and host immune system. Hindering iron uptake and disrupting adhesins' function could be a relevant antipseudomonal strategy. To test this hypothesis, we designed an iron-chelating glycocluster incorporating a tetrahydroxamic acid and α-l-fucose bearing linker to interfere with both iron uptake and the glycan recognition process involving the LecB lectin. Iron depletion led to increased production of the siderophore pyoverdine by <i>P. aeruginosa</i> to counteract the loss of iron uptake, and strong biofilm inhibition was observed not only with the α-l-fucocluster (72%), but also with its α-d-<i>manno</i> (84%), and α-d-<i>gluco</i> (92%) counterparts used as negative controls. This unprecedented finding suggests that both LecB and biofilm inhibition are closely related to the presence of hydroxamic acid groups.