The mottle-cheeked tyrannulet (Phylloscartes ventralis) is a generally common, small species of bird in the family Tyrannidae, the tyrant flycatchers.

[3] The mottle-cheeked tyrannulet has three subspecies, the nominate P. v. ventralis (Temminck, 1824), P. v. angustirostris (d'Orbigny & Lafresnaye, 1837), and P. v. tucumanus (Zimmer, JT, 1940).

Their wings are dusky with bright olive-yellow outer webs at the base of the flight feathers.

Both sexes of all subspecies have a dark brown iris, a long, flat, pointed black bill with a pinkish to yellowish base to the mandible, and slate to bluish gray legs and feet.

It is found from Minas Gerais state in southeastern Brazil southwest through Mato Grosso do Sul into eastern Paraguay and south throughout Uruguay and northeastern Argentina as far as Entre Ríos Province.

It forages actively, usually from the forest's mid-story to its canopy but sometimes lower in dense understory.

It perches horizontally, sometimes with its tail slightly cocked up, and makes short sallies to grab or hover-glean prey from leaves and twigs.

It typically forages singly or in pairs and sometimes joins mixed-species feeding flocks.

A nest of subspecies P. v. tucumanus was a ball made from plant fibers, dead leaves, lichen, and moss; it had a side entrance with a small "roof".

A nest of P. v. angustirostris was similar but made entirely of "Spanish moss" (Tillandsia usneoides).