Potent attacker Mclean arrived at City this Thursday after putting pen to paper on a two-and-a-half year deal with Bradford.
The signing of the former Hull City and Peterborough United forward should act to significantly strength the Bantams' attacking options as they begin the second half of their league campaign.
Following the recent departure of Nahki Wells to West Yorkshire neighbours Huddersfield Town, Parkinson reckons bringing someone of the calibre of Mclean into the football club will give the rest of his players a lift at just the right time.
Parkinson said: "I really felt the training ground needed a new signing. I thought the arrival of a new face around the place with give the lads a boost.
"We knew for a while that Nahki was most probably going to be leaving us, so myself, David Baldwin (Director of Operations) and the chairmen have been working really hard recently trying to put plans in place.
"We've worked a lot on getting this done because we felt the rest of the squad needed a lift and that the supporters probably needed a lift as well.
"Aaron is a character - he has a great personality - and that is going to be great for our dressing room.
"We originally tried to get Aaron in for last Saturday's game (vs Bristol City) put we just couldn't get it through in time for one reason and another.
"We've had to be patient and wait this week but I'm delighted it is all signed and sealed now.
"I've come across Aaron many times in my career as a manager. He is aggressive, he's quick, and he attacks the ball in the box.
"He's determined to do well here. He can play out in wider positions but we will be bringing him here as a down-the-middle striker - nothing else. That is where we feel his strengths are.
"He ticks all the boxes we were looking for really. There was a gap in our squad with Nahki going and it was important that we filled it."