He was the son of Rosanna (née McFadden) and Alexander Poynton; his mother was Irish and his father was from Liverpool, England.

His actions earned him a place as Commissioner for Crown Lands in the Solomon ministry in 1899, which lasted only eight days.

[2] In 1901 Poynton successfully stood for the Australian House of Representatives in the inaugural federal election as a Free Trade Party member for the Division of South Australia (which was not divided into electorates).

[2] During his time in parliament Poynton served variously as a member of the royal commission on stripper harvesters, chairman of committees, Treasurer, Minister for Home and Territories and Postmaster-General.

Among his political achievements was the establishment of a railway between Port Augusta and Western Australia, for which he lobbied nearly 18 years.

During fiery internal party debates on the issue of conscription during World War I, Poynton became a strong conscriptionist.