The 23-year-old joins the Sky Blues until the end of the season after making just five appearances for Blackpool this season.
"We are going into a crucial period in the season and with only two recognised strikers in the current squad it was vital we secured a third before Thursday's deadline," Coventry manager Steven Pressley told the club website.
"Nathan comes into the club with great potential, and at 23 years old he has still a lot to prove. We certainly hope he can make a big impression between now and the season's end."
The former Liverpool man spent a month on loan at fellow League One side Carlisle United earlier this season.