Coun Johnson, who only became leader of the council in December when he took over from former leader Julie Dore, has lost his seat in a devastating blow for the Sheffield Labour party.
The seat has been won by Christine Gilligan Kubo from the Green Party.
He polled 2,013 votes - the Greens won by a 334 majority.
Labour had a precarious hold on overall control of the council with only a seven seat majority.
Several seats have changed parties so far today and Conservative candidates are second in several seats too.
Follow our live blog on the election count here