Leptospermum sejunctum is a shrub that is endemic to the Nowra district in New South Wales.

It has thin, grey bark, lance-shaped to elliptical leaves, white flowers and fruit that remain on the plant at maturity.

The flowers are borne singly on short side shoots from adjacent leaf axils.

The fruit is a capsule about 8 mm (0.31 in) in diameter, the sepals having fallen off, and that remains on the plant when mature.

[2][3] Leptospermum sejunctum was first formally described in 1989 by Joy Thompson in the journal Telopea, based on plant material collected near Nowra in 1981.