Mclean, who trained with his new Peterborough team-mates this Tuesday, has penned a deal which will keep him at London Road until 28th January 2015.
The 31 year-old originally played for Peterborough between 2006 and 2011, scoring 78 goals in 174 appearances in the process for the Posh. Mclean also helped Peterborough secure back-to-back promotions from League 2 up into the Championship during the 2007/08 and 2008/09 seasons.
The forward can be seen settling back into life at Peterborough today (Tuesday) in the main article picture above. Image kindly provided by Joe Dent - Peterborough United.
Mclean moves to Peterborough on loan having failed to feature in any of City's last five fixtures.
He was an unused substitute for the matches away at Bristol City and Oldham Athletic before Bantams boss Phil Parkinson agreed to make the striker available for loan.
As a result, Mclean wasn't named in the match-day squads for the recent games against Doncaster Rovers, FC Halifax Town and Preston North End.
Mclean's previous outing for the Bantams before his move to Peterborough came during last month's televised home clash with Sheffield United. The forward has three goals to his name for City so far this season.
Speaking about Mclean's loan move to Peterborough, Parkinson said: "I'm pleased for Aaron to get this move. It is good opportunity for him to go there and get some games under his belt.
"Peterborough expressed an interest in him shortly after we made Aaron available for loan. I think Peterborough is the place where he wanted to go.
"There were a few other clubs interested in Aaron but I'm glad we've got this deal finally agreed for him and I hope he does well there."
Mclean will be eligible for Peterborough's forthcoming F.A Cup second round tie at Colchester United following City's decision to give Posh permission to play him in the competition.