Rubus macraei is a shrub with shedding bark. Its stems are prostrate or decumbent, sometimes rooting at the nodes, and are sparsely covered with slender prickles up to 3 mm long. The stems are also densely tomentose, with glandular hairs on younger parts. Both primocanes and floricanes are present, similar in form, somewhat thick, and coriaceous when dry. The leaves are palmately compound, alternate, with broadly ovate to suborbicular or rhombic–suborbicular blades measuring 5.1–8.5(–11) cm long and 3–6(–9) cm wide. Each leaf consists of three leaflets, with the terminal leaflet being the largest and the lateral ones slightly asymmetrical. The upper surfaces are uniformly sparsely pilose, occasionally with hairs more concentrated on or between the impressed veins, while the lower surfaces are usually densely velvety tomentose, though sometimes tomentose only along the raised veins. The margins are irregularly and usually coarsely serrate and often somewhat lobed. The leaves are petiolate, with petiolules 0.4–3 cm long and petioles 1.5–3.5(–7) cm long, moderately to densely tomentose, and sometimes bearing scattered small prickles. The stipules are narrowly oblong to linear–lanceolate and measure 0.8–1.5 cm long. The flowers are arranged in corymbose inflorescences, with 1–8 flowers per cluster. Each flower is bisexual, with pedicels 8–55 mm long that are densely tomentose and usually covered with slender prickles. The calyx consists of five persistent ovate sepals, 10–16 mm long, with both surfaces densely tomentose and the apex acuminate to caudate. The corolla consists of five dark pink to dusky rose obovate petals, each 13–16 mm long. Numerous stamens surround the superior ovary, containing numerous carpels on the raised receptacle. Each carpel is one-celled, with two ovules per cell and a filiform, subterminal, persistent style. The fruit is a juicy, dark red to dark purple ovoid drupe, measuring approximately 2.54 cm long and densely pubescent. Each drupelet contains a single seed. It is found on steep rocky slopes, open rocky areas in wet forests, the margins of bogs, and in sheltered thickets within pastures or subalpine shrubland between 1,610-2,080 meters.