The deal has seen Sky Blues right-back Jordan Clarke move the opposite way.
Martin, 25, spent a brief loan spell at Coventry last year while has was playing for Southampton.
"We tried to bring him back to the club on a permanent deal this summer so I'm delighted that we've been able to revisit discussions with him and bring him back to the club on a loan basis," manager Steven Pressley told Coventry's official website.
"In Aaron we now have another defensive player who can also pose a threat at the top end of the pitch, proven by the three goals he's already scored this season, so I'm excited by his arrival for a second spell with us."
Martin could be in action for Coventry on Saturday when they make the trip to Leyton Orient in League One.