This species is characterized by its rather dense hirtellous pubescence on the stems and inflorescences; its small, shortly bidentate stipules; its somewhat small, elliptic to oblanceolate leaves with generally four to six pairs of secondary veins that are weakly developed but visible on the lower surface but without domaita; its shortly pedunculate, several-flowered, cymose inflorescences; its small, apparently yellow flowers; and its small blue or perhaps sometimes white fruits. The identity of this species is not completely clear, whether this is a distinct taxon or a pubescent form of one of another species. One specimen is provisionally included here, Rakotonandrasana 480 from Zahamena: this specimen has all the characters of Psychotria baronii including of the the pyrene and endosperm, but its fruits are described on the label as red.

Bremekamp considered Psychotria baronii closely related to Psychotria ankafinensis, but noted that it has a consistently different aspect and thus he separated it. Psychotria baronii is also similar to Psychotria humbertii, which Bremekamp separated based on its pyrenes with a bisulcate adaxial furrow, vs. the pyrenes plane adaxially together with ruminate endosperm in Psychotria baronii.