The 21-year-old has struggled to get minutes under his belt this season, making just 11 appearances, while none of those have come under new City boss Steven Pressley.
And Cobblers manager Aidy Boothroyd has taken Cameron on loan to bolster his side's promotion push having worked closely with the defender during his time in charge of the Sky Blues between May 2010 and March 2011.
Boothroyd said: "I gave Nathan his debut in the Championship. He was one of the stand-out players of my time at Coventry.
"He is an England Under-19 international and has all the attributes required to be a top-class defender. Sometimes young players lose their way a little and a change of scene can do them the world of good and I have a lot of faith in Nathan's ability.
"For someone of 21 he has a fair bit of experience under his belt. He has had some ups and downs in his career already but I'm sure we can help get the best out of him. I know all about him, he is powerful, good in the air and quick and I am delighted he is here."
Sky Blues development director Steve Waggott added: "Nathan felt at this point in his career he wanted to be playing regular first-team football and manager Steven Pressley could not provide him assurances of that.
"We felt the best way forward for all parties was to provide Nathan the opportunity to go out on loan and we wish him all the best for the remainder of the season."
- Sports & Recreation
- Aidy Boothroyd