Kalophrynus baluensis is known only from the highland primary rainforests of Gunung Kinabalu, although it may also occur in neighboring highlands at similar elevations (around 1500 m above sea level).

It is a stocky, short-legged frog that is typically encountered on the forest floor, where its brown coloration provides excellent camouflage among the leaf litter. The call consists of a single, high-pitched whistle with long pauses between notes. The pitch, extended intervals, and effective camouflage make calling males very difficult to locate.

According to Inger and Stuebing (2005), females reach up to 39 mm in snout–vent length, with males being slightly smaller.

Little is known about the reproductive strategy of this species. However, Karlsson et al. (2018, Herpetological Review49[1]) provided evidence that K. baluensis is a phytotelma breeder, similar to other species in the genus. The team observed an amplecting pair in a tree buttress and shortly thereafter discovered eggs in that same buttress.

This frog has an interesting defense mechanism against predators: when threatened, it secretes large amounts of sticky, white slime. Although we did not test its properties, we assume the slime is not only adhesive but also potentially irritating or toxic.