Alexander Keith Johnston (1844-1879) was a Scottish explorer and geographer.

He was the son of Alexander Keith Johnston (1804-1871).

In 1873-1875 he was geographer to a commission for the survey of Paraguay; and he died in Africa while leading the Royal Geographical Society's expedition to Lake Nyasa.

Reference

• James McCarthy, Journey into Africa: The Life and Death of Keith Johnston, Scottish Cartographer and Explorer (1844-79) (Caithness, Scotland: Whittles Publishers, 2004) ISBN 1904445012