Nelsons Plains is a primarily rural suburb of the Port Stephens local government area in the Hunter Region of New South Wales, Australia. It is situated on Seaham Road between the Hunter and Williams rivers. At the 2016 census the suburb had a population of 362.

Nelsons Plains is a wedge-shaped suburb, bisected by Seaham Road, with the point of the wedge in the south-eastern corner where the Williams River joins the Hunter River. This part of the suburb is generally less than 2 metres (7 ft) above river level, making it subject to periodic flooding, as happened during the June 2007 Hunter Region and Central Coast storms. In the north-eastern corner of the suburb elevations reach up to 42 m (138 ft) but to the east of Seaham Road, between the road and the Williams River, the ground slopes quickly downward to a height of less than 2 m (7 ft) above river level, making this part of the suburb also subject to flooding.

At the 2016 census the population was 362, with a median age of 41 and 89.6% of the population spoke only English at home. Australian born residents represented 88.8%, with 2.0% born in New Zealand and 0.8% in England. For religion, 31.4% identified as Anglican, 28.3% as Catholic, 18.9% as having no religion, 7.5% did not state a religion and 5.8% belonging to the Uniting Church.