On Monday, Gianfranco Zola resigned from his position in the dugout at St Andrew's after the Blues suffered a 2-0 defeat at home to Burton Albion, taking his record at the club to just two wins from 24 matches.
However, the West Midlands outfit have wasted no time in naming his successor, with 70-year-old Redknapp being brought in to try to keep the team in the second tier.
Redknapp is vastly experienced in English football after spells with Bournemouth, West Ham United, Portsmouth, Southampton, Tottenham Hotspur and Queens Park Rangers since he started his managerial career in 1983, but he has not featured in the dugout on the domestic scene since February 2015.
He arrives in Birmingham needing to get an instant response out of a team who now sit in 20th position in the Championship table, just three points above the relegation zone.
The club face a testing end to the campaign, with the second-city derby away at Aston Villa coming up on Sunday, before they end the season with matches against promotion-chasing Huddersfield Town and in-form Bristol City.