Awarded city status by Queen Elizabeth II, the receipt of letters patent makes it officially a city.
Britain's oldest recorded town has officially become the UK's newest city.
The former Roman settlement of Colchester was named one of eight towns to be made cities to mark the Queen's Platinum Jubilee.
On Wednesday, the parchment letters patent were presented to the mayor Tim Young.
A procession moved from the Mercury Theatre to the Town Hall where the documents were presented by His Majesty’s Lord Lieutenant of Essex Jennifer Tolhurst.
In her address to the council inside the Moot Hall, Ms Tollhurst said the time had "undeniably come" for Colchester to be made a city.
She presented the letters patent to the mayor which marked the moment the town became the 76th city of the UK.
Mr Young thanked everybody involved in the day and said he was "humbled" to be the first city mayor.
"Colchester is a city with a bright and thriving future," he said.
Lt Col Ed Rankin, commander of Colchester Garrison, said there was "a real sense of shared pride” that Colchester was now a city.
Philip Wise, heritage manager at Colchester City Council (formerly Colchester Borough Council), said: "Throughout the Roman period for about 350 years Colchester was a city.
"But then people forgot about us in the Middle Ages and started to regard Colchester as a town so we've had to wait a very long time to have our city status restored."
Colchester: 'We've had to wait a long time for our city status'
