Ferdinand and coach Chris Ramsey were placed in temporary charge of the first team in the hours following Redknapp's shock decision to quit the club on Tuesday.
But Ramsey and Redknapp's long-time assistant Kevin Bond will now take on the day-to-day running of the first team as Ferdinand settles into a new role.
That leaves Rangers still looking for a permanent manager, and Tim Sherwood's position at the head of the Sky Bet market will surely only strengthen given Ferdinand was considered his likeliest rival. The pair worked together, along with Ramsey, during Sherwood's time as Tottenham boss last season.
In the meantime, owner Tony Fernandes has given his new director of football a specific brief - "to develop a philosophy of buying young, hungry players."
Former QPR striker Ferdinand returned to the club in October as head of football operations, and Fernandes told the club website: "I've been really impressed with the job Les has done in his short time here and as such I am keen for his role to evolve, with the clear mandate of assisting us in developing and evolving the footballing department, from the academy to the first team.
"This is a new strategy for us. Our recruitment policy at QPR is changing. I've had many messages from supporters, of all ages, who aren’t - for one reason or another - satisfied with what’s going on at QPR at the moment, but I can reassure all Rangers fans that we are putting the building blocks in place to move things in the right direction for the future.
“We’ve made a number of mistakes in the transfer market over the last few years and it’s something we want to change. We don’t want to be a buying club - we want to nurture young talent and build a young, ambitious team.
“Premier League survival is our priority in the short term, but in the medium and long term we want to make sure everything is in place, from the academy upwards, to create a culture and philosophy within the club that QPR fans can be proud of."
Ferdinand said: "Everyone knows what this club means to me and if anything the last few months have only enhanced the feelings I have for QPR.
"Working closely with Tony and the Board, I can assure QPR fans that they are desperate to create a lasting legacy at Loftus Road and the role of Director of Football will be hugely important."
The departures of coaches Glenn Hoddle and Joe Jordan, meanwhile, have been confirmed.