The England international made the surprise decision to call time on his north London career following a £40m move to top-four rivals Liverpool FC on deadline day in the summer transfer window.
Oxlade-Chamberlain turned down the chance to sign a new contract at the FA Cup holders, while he rejected a move to defending Premier League champions Chelsea despite passing a medical at the west London club.
The 24-year-old made a slow start to his Anfield career but the versatile midfielder has since established himself as a first-team regular following two goals and two assists in 17 Premier League appearances.
The England international scored Liverpool FC’s fifth goal in a 5-0 win over the Premier League’s basement club Swansea City at Anfield on Boxing Day.
The former Southampton starlet spent seven seasons at Arsenal but started to regress under Arsene Wenger in recent seasons.
Former Liverpool FC captain Redknapp believes Oxlade-Chamberlain made a great decision to kick-start his ailing Premier League career with a summer move to the Merseyside outfit in the summer.
“It’s probably unfair to question how he was coached under Arsene Wenger but I watched him play and I didn’t feel he developed for years,” Redknapp told Sky Sports.
“It looked like he was standing still. I feel a lot of players at Arsenal are in a similar situation.
“You can go and sign a new contract and say ‘OK, I’ll be on the bench’, but he has taken a risk in his career.
“He could have stayed at Arsenal and signed a new contract but he wanted to challenge himself and has gone to live up north and given himself a chance to play in the first team.”
Redknapp added: “He wasn’t guaranteed a spot but he is in now and it will be hard to dispossess him of the shirt.
“It was a really bold move for him and one that is really paying off. Look at how much he is improving, he has got fitter, stronger, and he is a different player than he was at Arsenal.”
Liverpool FC haven’t won the Premier League title.
MORE: Man United latest news
MORE: Arsenal latest news
MORE: Chelsea latest news
MORE: Liverpool latest news