William Johnson Kerr (1787 – April 23, 1845) was a political figure in Upper Canada.
He was born in 1787, the son of Robert Kerr and grandson of Sir William Johnson.
In 1818, he participated in meetings organized by Robert Gourlay and presented a list of grievances to Lieutenant Governor Sir Peregrine Maitland.
He served as superintendent for the Burlington Bay Canal project, alongside Michael Tipson.
In 1832, no longer sympathetic to the reform cause, he took part in an assault on William Lyon Mackenzie in Hamilton and was charged and fined.