Polypedates macrotis is a lowland species inhabiting primary and good-quality secondary forests. The type locality lies in the Baram District, Sarawak.

Adult males reach up to 60 mm and females up to 85 mm in snout–vent length. The head is broad and flat, triangular in dorsal view. The eyes are conspicuously large and directed slightly forward. Long legs, elongated digits, a relatively slender build, and wide adhesive discs reflect the strongly arboreal lifestyle of this species. A faint supratympanic fold is present and curves around the upper margin of the eardrum. The eardrum itself is large and clearly visible. The pupil is horizontal and elliptical. P. macrotis resembles Polypedates leucomystax, but differs in several features; for example, the eyes appear larger and more forward-oriented, and the fingers longer with relatively broader adhesive discs.

The dorsal skin is smooth, lacking warts or pronounced tubercles. A whitish ridge on the outer side of the forearm is common.

Coloration is highly variable but usually dominated by brown tones. Two dark longitudinal bands extending from the snout to the posterior body are typical, though in some individuals these are replaced by a spotted pattern. A dark mask originates at the naris, follows the canthus rostralis, and continues behind the eye to encompass the eardrum, extending posteriorly below the supratympanic fold; sometimes it is continued by a series of dark blotches to the groin. The extent of this mask varies across populations. The dorsal surfaces of the limbs bear dark crossbars. The underside is mostly white. The iris is pale golden to bronze, with variably wide dark brown anterior and posterior sectors.

Polypedates macrotis breeds in stagnant or slow-moving waters such as ponds and ditches. Eggs are deposited in foam nests, which are attached to leaves or twigs overhanging the water. Tadpoles are brown dorsally, with a whitish belly and a pigmented gular region. The larval eyes are positioned laterally, and an orbitonasal streak is clearly visible. Tadpoles reach up to about 60 mm in total length. The tail fin narrows to a pointed tip, forming a slender flagellum.