The ex-Chelsea manager has been brought in to assist Paul Hart on the south coast and he plans to use his previous experiences in England's top flight to help the club he was appointed technical director of in 2006 climb out of the drop zone.
"I'm very happy to be back in football," he told Mirror Football.
"Since I left Chelsea I have missed the involvement and it's great that I can come back to the club where I started in English football, a club I know well and where my Premier League adventure began.
"I have very good memories from my first spell at the club and was delighted to be able to come back to Portsmouth.
"I'm very happy to be working with Paul again. I know him well from before," he added.
"Everyone at the club knows how I worked with Harry Redknapp when I was here before and that it will be the same this time round.
"Whatever the club needs me to do, I will do it. I will be there to help him and the club, to help them stay in the Premier League."