Glyphoglossus species are among the most enigmatic frogs of Borneo because they spend most of their time underground. Occasionally, under the right weather conditions, adults of G. flavus may suddenly appear in large numbers to breed explosively. A clutch was photographed by Maximilian Dehling. The photo shows a single-layer egg mass floating on the water surface, containing relatively small, light-grey embryos. Surface-floating, single-layered egg masses are common among microhylid species in general.

The body shape of G. flavus is similar to that of other Bornean Glyphoglossus species (see descriptions of other species), although the head in this relatively small species (35 mm) is not as broad as in some congeners. The characteristic yellowish body color, particularly in the posterior part of the body, gives the species its name.