Peperomia tetraphylla is a fleshy herb with reddish-purple to green stems, ascending or decumbent, and often rooting at the nodes. These stems can range from 8–30(–40) cm long and 4–6 mm in diameter at the base, displaying dichotomous or trichotomous branching. Internodes vary in length from 1–4(–8) cm and are puberulent, with hairs measuring 0.1–0.2 mm long, though older stems may become glabrate. The leaves are simple, with arrangements that are either opposite or whorled (2)3–4 per node. The leaf blades are broadly rhombic-elliptic to suborbicular, occasionally broadly ovate or obovate, measuring 0.7–2 cm in length and 0.5–1.7 cm in width. They have broadly obtuse to rounded or obtuse apices and rounded to cuneate bases. The leaf surfaces are sparsely puberulent, or the upper surfaces may sometimes be glabrate. They are yellowish-green to dark green on the upper surfaces and slightly paler on the lower surfaces, thick and turgid when fresh, and become wrinkled and coriaceous when dry. The leaves feature flat margins and are palmately 3-veined, with the veins being obscure and paler than the intercostal areas. Petioles are erect and approximately 0.2 cm long. The flowers occur in solitary spikes that are terminal, ranging from 3–6.5 cm long with a rachis diameter of 3.5–6 mm, and are puberulent. These flowers are densely congested along the spike and are supported by peduncles 1–6 cm long. A peltate bract subtends each flower, lacks a calyx (sepals) and corolla (petals), and contains two stamens. The ovary is superior, cylindrical-ovoid, 1-carpellate, and deeply embedded in the pits of the rachis with a slightly oblique apex. The fruit is yellowish in the lower half, cylindrical, about 1.2–1.3 mm long, smooth, slightly beaked apex, and papillose-viscid with sessile glands. Each fruit contains one seed with a scanty endosperm and a copious, starchy perisperm. It is found in shaded or sometimes open sites, on rocks that may be moss-covered, and occasionally epiphytic on moss-covered trees. It thrives in various environments, from mesic to wet forests, subalpine forests, and alpine deserts, between 70-2,290 meters.