And after today's 3-1 home defeat to Preston, Birmingham chose to sack the 70-year-old.
Redknapp - who embarked on a rebuilding programme at City over the summer, which included the club-record signing of Jota - took over after Gianfranco Zola's disastrous reign last season.
The 70-year-old took charge of 13 games, and signed 14 players over the summer - but despite managing to keep the Blues up at the end of last season he left Birmingham with the club second from bottom in the Championship.
Redknapp's side had not won since August 12 and the 3-1 defeat at home to Preston was their fifth in a row in the league, with another in the cup.
Last season the former QPR manager, who hadn't been seen as a manager in this country since his spell there ended because of a knee injury- with the club in a awful position, took over from Birmingham to keep them up.
Air Force Drops 29-13 Contest at #7 MI
Ty Isaac led the ground attack with 89 yards on 16 carries, and Karan Higdon had a 36-yard rushing touchdown with 1:02 remaining. This will be another week MI wins but the RZ numbers are bad and Speight has been one of the most inaccurate passers in power 5.
No. 25 UCLA comes up short in Memphis barnburner
The receiving end was taken care off by Theo Howard who made game-high 110 yards receiving on seven catches with a score. Memphis' Riley Ferguson upstaged Rosen with six touchdown passes to lead the Tigers to a 48-45 upset of No. 25 UCLA.
Louisiana-Lafayette at Texas A&M
That one victory came against A&M 21 years ago in Lafayette, when the town partied for days afterward. Those were among eight Aggie turnovers, four of them interceptions off quarterback Brandon Stewart.
But despite investing heavily in new players over the last few months, Birmingham have made a decision to axe the 70-year-old after six successive defeats, which sees them sitting second from bottom of the Championship.
Meanwhile Lee Carsley, the club's Head Professional Development Coach, has been placed in caretaker charge of the club while they search for a fourth manager in the space of a year. It was just rank, poor play from us that cost us goals.
"We started the second half well, on the front foot, we get a corner then after that they came on to us and we couldn't handle it".
"You stand there as a manager, what can I do about that?"