The Conservatives have taken control of Harlow Council from the Labour Party for the first time in nine years.
Labour held on to just one of the seven seats it was contesting and council leader Mark Ingall lost his seat.
The Conservatives also took control of Basildon Council, which had been no overall control.
After Thursday's Essex County Council elections, the Conservatives held their position as the majority party despite losing four seats.
The party won 52 of the 75 seats up for grabs, but lost four from 2017.
The Lib Dems now have eight (up one), independents took six (up two) and Labour has five (down one).
Kevin Bentley has been chosen by the Conservatives as the new county council leader. Louise McKinley has been named as deputy leader.
Mr Bentley has been acting leader of the authority after previous leader David Finch decided not to stand for re-election.
In Harlow, the Conservatives now have 20 seats on the district council compared with the 12 held by Labour.
Mr Ingall said in a tweet he was "disappointed" about both losing his seat and his party losing control.
"I am proud to have served as a Labour councillor and proud to have represented Bush Fair," he said.
In total, the Tories gained 12 of the 13 seats being contested in the town.
While Essex as a whole is a strong blue county, the strength of the gains over Labour in Harlow and Basildon shocked the opposition, even some Tories.
There was talk in Harlow of a stalemate this week where both Tories and Labour would be on 16 seats each. Instead, nine years of a Labour majority-run council was overturned. Labour lost all but one of the seven seats it was defending. The Bush Fair ward elected its first Conservative ever, taking out the Labour leader in the process.
Basildon's Labour leader knew he'd lost the top job within 90 minutes of the count starting. Gavin Callaghan held on to his Pitsea seat, but three other seats Labour thought were safe were lost as the Conservatives took control of the council. His Twitter status became "former Leader of Basildon Council" and senior members of the party left the count.
By Friday lunchtime, the Conservatives passed the 38-seat mark to secure their majority on Essex County Council. No surprise there.
But the Lib Dems outperformed their 2017 result and picked up seats, winning eight, as did independents and residents parties who picked up nine. The Conservatives will have a majority of around 50, six less than the high watermark of May 2017 when Theresa May was riding high in the polls.
The MP for Harlow, Conservative Robert Halfon, said he was "proud" that the Tories had seized control, tweeting that the authority was now under Conservative control for "only the second time in the history of our town".
Mr Halfon also offered "commiserations to the many hard-working" Labour councillors who had lost their seats.
"Whatever our significant political differences, all political parties want to build an even better Harlow and help people through Covid," he said.
Elsewhere in Essex:
- Southend-on-Sea Borough Council, a unitary authority, remains in no overall control
- Colchester Borough Council remains in no overall control
- Basildon Council had been no overall control, but became a Conservative majority
- Thurrock Council, Essex's other unitary authority, sees Conservatives increase lead
- Brentwood Borough Council sees Conservatives increase lead
- Rochford District Council remains in Conservative control
- Epping Forest District Council held by the Conservatives
- Castle Point's largest grouping is of independent councillors as the Tories lost seats
Of the 17 seats up for election in Southend, the Conservatives gained two seats - Belfairs and Shoeburyness - from independent candidates.
The Conservatives lost control of Southend in 2019 when they lost seats to Labour, the Lib Dems and independents.
In Colchester, the Lib Dems have been running the council in a coalition with Labour, but of the 19 seats up for election, they lost to the Green Party in Castle ward, to Labour in New Town and Christchurch, and held onto Shrub End with a majority of only 36.
They did, however, take Wivenhoe from Labour.
The Conservatives have 23 seats (no change), the Lib Dems have 12 (down one), Labour has 11 (no change), Greens have two (a gain of one seat), with three other seats filled the Highwoods Group.
Green councillor Steph Nissen tweeted that she was "absolutely delighted" to be elected for the first time.
"I am looking forward to getting stuck in... and helping make our town an even better place to live," she said.
In Castle Point, there are now 21 independent councillors, mostly from the Canvey Island Independent Party, as the Conservatives lost three seats leaving them with 20. No other parties have councillors.
- Essex County Council results
- Harlow Council results
- Southend-on-Sea Borough Council results
- Colchester Borough Council results
- Basildon Borough Council results
- Thurrock Council results
- Brentwood Borough Council results
- Rochford District Council results
- Epping Forest District Council results
- Castle Point Borough Council results
More Tory successes
The Conservatives also swung Basildon Borough Council in their favour, a council which previously had no overall control, but had a Labour leader.
The Tories now have 22 seats (up four), Labour has 12 (down two) and there are eight independent councillors (up one).
The party also increased its control of Thurrock Council by one seat, taking Chadwell St Mary from Labour.
Labour gained a seat in Tilbury St Chads from an independent, meaning the party's overall number of seats at the unitary council stays the same.
The Conservatives have 29 seats, Labour has 16, Thurrock Independents have three (no change) and there is one other independent.
In Brentwood, the Tories increased their hold on the borough council, taking seats from Labour, the Liberal Democrats and an independent.
The Conservatives now have 22 councillors (up three), the Lib Dems have 13 (down one) and Labour have two (down one).
They also held on to Rochford and Epping Forest councils.
- England local elections 2021
- Brentwood Borough Council
- Castle Point Borough Council
- West Thurrock
- Epping Forest District Council
- Harlow District Council
- Essex County Council
- Southend-on-Sea Borough Council
- Thurrock Council
- Colchester Borough Council
- Basildon Borough Council
- Uttlesford District Council