A new species and genus of a passerine bird from the early Oligocene of Poland is described. Resoviaornis jamrozi gen. et sp. nov. is the third nearly complete passerine known so far from the Paleogene. As in the two recently described passerine birds, it shows a mosaic of characters typical for the Oscines or Suboscines, and therefore its systematic position within Passeriformes remains unresolved, pending discoveries of new specimens. The specimen is so far the oldest passerine to have the coracoid with well pronounced and hooked processus acrocoracoideus. With the size of the extant Blue Tit, it is also the smallest of the Oligocene passerines. The slender remnants of its beak point to an insectivorous or frugivorous bird, and the relatively long legs suggest that it spent much time on the ground.