Gyrinus convexiusculus is a species of whirligig beetle in the family Gyrinidae, first described by Macleay in 1871.

[2] The species is 3.5–4.8 mm long, and is the smallest Australian whirligig beetle.

[3] Gyrinus convexiusculus found in New Zealand are consistently larger than Australian specimens (averaging 4.4mm for males and 4.6mm for females).

[3] The species has been recorded in South Asia,[4] China, Indonesia, New Zealand and New Caledonia.

[2] The species is found in shallow fresh water bodies,[3] small peat lakes and man-made dams.