UKIP's Kerry Smith has won the party's first county council seat in Essex at Basildon Westley Heights with a majority of 139.
The seat was won by the Conservatives in 2009.
Essex did have one UKIP councillor before the election but he had defected mid-term after being elected an Independent in Canvey Island.
Regardless of the result in Thursday's election, Northamptonshire will have fewer county councils because of boundary changes.
The Tories have been sent a warning in their traditional Essex heartland, losing nine county council seats to a bullish UKIP.
Suffolk County Council has been Conservative-controlled since 2005. On Thursday there were elections for 75 councillors.