Swainsona oliveri is a slender prostrate to ascending annual or perennial herb, that typically grows to a height of about and has radiating stems. The leaves are imparipinnate, mostly long with 9 to 13 egg-shaped leaflets with the narrower end towards the base, the side leaflets long and wide with
stipules long at the base of the
petioles. The flowers are cream-coloured to yellow, sometimes tinged with pink, arranged in racemes of up to 4 on a
peduncle up to long. The
sepals are joined at the base to form a tube about long, with lobes shorter than the tube. The
standard petal is long and wide, the
wings long and the
keel about long and deep. Flowering occurs from August to September, and the fruit is a narrowly elliptical
pod long and wide with the remains of the
style long. ==Taxonomy and naming==