Lennon had been without a club since leaving Burnley at the end of the 2021/2022 season.
The tricky winger started his career at Leeds United but produced his best football during ten years at Tottenham Hotspurs, where he won the League Cup in the 2007/2008 season.
Lennon also turned out for Everton and Turkish side Kayserispor during the latter stages of his career.
Lennon also won 21 caps for England and played at the 2006 and 2010 FIFA World Cups.
"I've finally decided that the time is right to hang up my boots, having weighed up my options I didn't feel any were right for me or for my young family," Lennon wrote on social media.
"It has been a very tough decision as football has been my life since probably the age of three and the last 20 years playing professionally at the top has been so amazing. I've loved every minute of it!
"Football means so much to me and always will do. I don't think I even realised how much until I started considering this retirement, it has been everything and more.
"Now I'm very excited for this next chapter in my life and spending a lot more time with my loved ones. There is so much I want to do and give back with all my experience and my experiences on and off the pitch and will be doing so in the near future.
"Football world, thank you from the bottom of my heart."
