The Wilmslow-born 22-year-old has linked up with Hayden Mullins' U's and will remain at the JobServe Community Stadium until Saturday, 1st January, 2022.
Turner, who began his career at Bolton Wanderers, completed a season-long loan to League Two side Morecambe last term, making his professional debut for the Shrimps before being recalled to the Magpies in January.
The England under-19 international joined United's Academy in the summer of 2019 and has made 25 competitive appearances for Newcastle's second-string during his two years on Tyneside.
Colchester, who finished 20th in League Two last term, kick off their 2021/22 campaign this afternoon away at Carlisle United.