England and Essex legend Alastair Cook has announced his retirement from professional cricket, ending a record-breaking 20-year career.

Cook's contract at Chelmsford has expired and England's all-time leading run-scorer is not seeking an extension.

"It is not easy to say goodbye. Cricket has been so much more than my job," said Cook in a statement.

"It has allowed me to experience places I never dreamed I would go, be a part of teams that have achieved things I would never have thought possible and, most importantly, created deep friendships that will last a lifetime.

"From the eight-year-old boy who first played for Wickham Bishops Under-11s to now, I end with a strange feeling of sadness mixed with pride. Above all, I am incredibly happy."

Essex had been waiting on a decision from Cook following the end of the County Championship season, when they finished second behind champions Surrey.

Coach Anthony McGrath said he was hopeful the county would "see him for a bit longer", but Cook informed Essex he would be retiring on Thursday evening.

"It is the right time for this part of my life to come to an end," added Cook. "I have always given absolutely everything I possibly could have to be the best player I could be, but now I want to make way for the new generation to take over.

"I will never underestimate the privilege I have had to play cricket. I will always be grateful for what the game has given to me. Now, I hope the Bedfordshire Farmers will find space for a has-been 'all-rounder' somewhere in their lower order."

Cook made his professional debut against Essex for Essex Cricket Board in the Cheltenham and Gloucester Trophy in 2003, then played in the County Championship for Essex later that summer.

He made a double hundred for Essex against the touring Australians in 2005, and the next year was famously called up from an England Lions tour in the West Indies to make his England Test debut against India in Nagpur, scoring a century in the second innings.

It would be the start of a 161-cap Test career, 159 of them played consecutively, a world record.

Cook's 12,472 Test runs and 33 centuries are England records, while no batter for any team has made more than Cook's 11,845 runs as a Test opener.

He was England Test captain between 2012 and 2017, leading in 59 matches, then a record which has since been broken by Joe Root.

Cook captained England to Ashes series wins on home soil in 2013 and 2015, but was also the leader on the wrong end of a 5-0 hammering down under in 2013-14. He was captain for 69 one-day internationals between 2010 and 2014.

Cook's crowning glory was the 766 runs he scored to be player of the series during the 2010-11 Ashes win in Australia, England's only triumph in an away Ashes since 1986-87.

The end of his Test career, when he was only 33, was fairytale stuff. Announcing his retirement before the fifth match of the series against India five years ago, Cook marked his final match as an England player with a century amid emotional scenes at The Oval, with his wife Alice heavily pregnant with their third child.

"Although my England career came to an end in 2018, I remain blown away by the amount of affection I receive from England supporters," said Cook.

"Wherever I have travelled, you have been there with your enthusiasm, kind words and unshakable belief. English cricket really does have the best fans in the world."

Cook initially signed to play three more years with Essex, the county he joined as a 12-year-old.

He was part of the team that won the County Championship in 2019, repelling the Somerset spinners on a tense final day of the season at Taunton.

Essex were in with an outside chance of regaining the title until the final round this season, only to lose out to Surrey. The last of Cook's 352 first-class matches came away to Northants. He was out for six in each innings, both times to Ben Sanderson.

Overall, Cook ends on 26,643 first-class runs - comfortably higher than anyone else currently playing the game - at an average of more than 46, with 74 hundreds.

Since the end of his England career, Cook's 3,889 runs in the County Championship and Bob Willis Trophy is bettered only by Durham's Alex Lees.

He also played a total of 178 List A matches and 32 T20s, making 14 white-ball hundreds.

"I won't miss strapping on my pads and facing the new ball, but I will miss being in the Essex changing room," said Cook.

"When I ended my international career, I had no idea that I would have five more bonus years playing for Essex. I cannot put into words just how much fun we have had during that time."

Cook was knighted for services to cricket in 2019. At the time he was the first England cricketer to receive a knighthood since Ian Botham in 2007.

James Anderson, England's all-time leading wicket-taker, said Cook has had an "amazing" career.

Caught Cook, bowled Anderson occurred on 40 occasions in Test cricket, the most for any fielder-bowler combination for England.

"I feel very fortunate that I got to play a lot with him," said Anderson. "For him to give back to Essex what he has over the past few years speaks volumes about him.

"He constantly performs, churning out runs. He'll be hugely missed."

Former England captain Michael Vaughan said: "I don't know if we'll see a player like him again. He's the last of a dying breed of openers. He maximised every ounce of his ability to the maximum level.

"He was a great team member and a great ambassador for the game."

Root, who succeeded Cook as England captain and is on course to break his run-scoring records, described his former team-mate as the "greatest ever".

"I'm very grateful for what he gave to me and other young lads in my position. He's been incredible for the game," Root told PA Media.

"What he did for England, we all know how special that was. It was a memorable start to his career and a memorable finish."