In this paper, a class of wideband filtering microstrip (MS)‐to‐microstrip (MS) vialess vertical transition is proposed and demonstrated on coplanar waveguide (CPW) multi‐mode resonator (MMR) formed on their common ground plane. Then, resonant mode in the proposed CPW MMR can be properly excited by setting a certain offset distance between two feeding points, which realizes good signal transmission between the top‐ and bottom‐layer MS lines over a wide frequency range. After that, to facilitate the design process, a synthesis design method is introduced for application in design of the proposed MS‐to‐MS vialess vertical transition with the prescribed design specifications. Finally, by virtue of the proposed CPW resonator, one design example, that is, a four‐pole wideband filtering MS‐to‐MS vialess vertical transitions, are designed, fabricated, and measured. The expected responses, simulated results and measured results of the proposed four‐pole MS‐to‐MS vialess vertical transition is in reasonably good agreement with each other, thus firmly validating the claimed superior performance of the proposed MS‐to‐MS vialess vertical transition on MMR.