The 1879 City of Dunedin by-election was a by-election held on 15 July 1879 in the electorate in Dunedin during the 6th New Zealand Parliament.
The by-election was caused by the resignation of the incumbent, Robert Stout.
The winner of the by-election was William Downie Stewart Sr.
His opponent Charles Reeves "got the Catholic block vote" and religion in education was a factor in several by-elections in 1879 (e.g. in Auckland and Nelson).