The winger, impressed many during his loan spell at the Ricoh Arena and the Sky Blues wanted to take him back on a season long loan.
However, when Steve Bruce and former City boss Eric Black took over at the Stadium Of Light, they were also impressed by Henderson and he has spent the season playing Premier League matches.
Such have been his performances that he was offered and subsequently signed a five year deal.
Former Coventry City loanee keeper Marton Fulop has been lined up to replace the injured Shay Given at Manchester City. Fulop is third choice at the Stadium Of Light and there are rumours that City may make the deal a permanent one when the transfer window reopens.
Former Coventry City loanee Courtney Pitt has been released by Cambridge United. The winger was one of a number of players being allowed to leave by the Conference side.
Kasper Schmeichel has agreed to cancel his five year contract at Notts County and is expected to leave at the end of the season. Former City midfielder Jonnie Jackson is expected to stay at the League Two Champions.