The 34-year-old, who left Southampton at the end of last season, scored more than 100 goals for Arsenal and won 47 England caps in a professional career that began in his early teens.
Walcott had been linked with a move to Bournemouth along with League One outfit Reading.
But, as talkSPORT told you on Thursday, has decided to call time on his career.
On Friday morning, he posted a video of his career from Sunday league to the Premier League and which has seen him win three FA Cups and two Community Shields.
"The first moment I put my football boots on aged 10, was the start of a special journey for me," he said.
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"From playing in the park with friends, to performing in some of the biggest stadiums, in front of huge crowds across the world.
"The support shown to me throughout this time, has been incredible in every way imaginable and I am truly grateful.
"I've shared the football pitch with so many incredible players and we have created so many unforgettable memories.
"I would like to say a big thank you to all the managers and coaches I've worked with, especially Harry Redknapp for giving me the start and Arsène Wenger for showing belief and support to me when I joined the club at only 16 years old."
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Walcott then listed his most treasured memories.
"The early days at Southampton football club, my transfer to Arsenal where I spent 12 enjoyable years and scored over 100 goals. Winning the FA Cup and scoring in the final which is every kids dream. To have had the opportunity to represent England 47 times, going to the World Cup in 2006, aged just 17 and still to hold the record for the youngest ever debut by a senior England player and youngest hatrick goalscorer at 19 - I will never forget that feeling.
"Goodison Park is such a special place to play and Everton will always be in my heart, I loved my time there and will never forget the way the fans welcomed me and my family.
"Then finally back to Southampton to complete the circle. It's a great club with an exciting young team that I know will get better and better. I'm lucky enough to have had offers to continue playing, but it feels right to finish where I started and hang up my football boots.
"Thank you to everyone who has been with me along the way."
In total, Walcott featured 563 times during his club career, where he banged in 129 goals in all competitions, with 80 coming in the Premier League.
The bulk of his career was spent in north London after he joined the Gunners in January 2006 aged 16 from the Saints for an initial £5million fee rising to £12m.
Despite not featuring for Arsenal in the second half of the 2005/06 season, then-England boss Sven-Goran Eriksson named him in his World Cup squad.
But the winger failed to feature in Germany, though he did become the Three Lions' youngest player at the age of 17 years and 75 days when he appeared in a friendly win over Hungary in May 2006.
Walcott's debut for Arsenal came in August 2006, where he supplied the assist for Gilberto Silva's equaliser against Aston Villa - the club's first Premier League goal at the Emirates.
His first strike for Arsenal came in the 2007 League Cup final against Chelsea, though the Blues ultimately ended up as 2-1 winners.
As he became a first-team regular under Arsene Wenger, he earned an England recall in 2008, where he scored a memorable hat-trick against Croatia.
He remains the youngest player to ever bang in a treble for the Three Lions - doing so at the tender age of 19.
Walcott's best personal season came in the 2012/13 campaign, where he fired in 21 goals in all competitions for Arsenal.
An injury picked up against Tottenham in the FA Cup third round in January 2014 saw him miss the final victory over Hull - along with 11 months of action.
Though his iconic gesture to the travelling Spurs supporters where he lifted up two fingers to symbolise the 2-0 scoreline as he left the pitch on a stretcher will live long in the memory of the Arsenal fanbase.
He quickly made up for lost time, with his fine performances seeing him named in the 2015 FA Cup final, where he opened the scoring in the 4-0 win over Villa.
After 12 years at Arsenal where he banged in 108 goals in 397 matches, Walcott opted to make the move to Merseyside to join Everton in January 2018.
But he was on the move again in 2020 - returning to St Mary's on an initial loan deal, before it was made permanent.
His second spell on the south coast saw him fire in five goals in 58 games.
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Unable to keep Southampton in the Premier League last term, the Saints opted against handing Walcott a new contract.
And Walcott, who has been a fan favourite at all three of his clubs, has now decided to call it quits after an 18-year career.