The Eurasian tree sparrow is 12.5–14 cm long, with a wingspan of about 21 cm and a weight of 24 g, making it roughly 10% smaller than the house sparrow.

The Eurasian tree sparrow has no true song, but its vocalisations include an excited series of tschip calls given by unpaired or courting males. 

The Eurasian tree sparrow reaches breeding maturity within a year from hatching, and typically builds its nest in a cavity in an old tree or rock face. Some nests are not in holes as such, but are built among roots of overhanging gorse or similar bush.

The Eurasian tree sparrow is widespread in the towns and cities of eastern Asia, but in Europe it is a bird of lightly wooded open countryside, with the house sparrow breeding in the more urban areas.