The Manchester United legend, who recently left DC United in the US, has signed a three-and-a-half year deal with the Blues and has assembled quite the backroom team.
There are several former Premier League players and people the former England international trusts as he looks to build on John Eustace's excellent work.
Birmingham are currently sixth in the Championship, so the pressure will immediately be on Rooney and his staff.
Rooney's backroom staff at Birmingham City
Ashley Cole
Perhaps the biggest name in Rooney's backroom staff and a young coach with vast experience already.
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As a player, Cole made over 100 England appearances and won countless trophies with Arsenal and Chelsea.
Since retiring, he has worked with Chelsea and Everton as Frank Lampard's assistant and will remain in his current role as England Under-21s assistant.
The 42-year-old played a key role in helping the Young Lions win the Under-21s Euros this summer and will now get to work with Birmingham's players.
John O'Shea
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O'Shea played 202 times with Rooney while the pair were at Old Trafford until he left to join Sunderland in 2011.
Therefore, the duo know each other extremely well.
And since hanging up his boots, the Irishman has worked at Reading and Stoke as an assistant manager.
He is also currently the number two for the Republic of Ireland and will remain in that role.
Carl Robinson
Robinson is a 46-year-old from Wales who claimed 52 appearances for his country.
He played for Wolves, Portsmouth and Sheffield United, among others, before moving to America and retiring in 2012.
Robinson started as an assistant manager with Vancouver before becoming the club's boss in 2013 and winning the Canadian Cup in 2015.
He met Rooney at DC United and will now return to the UK after leaving in 2007.
Pete Shuttleworth
Shuttleworth is a 48-year-old who started his coaching career with Worksop.
He then worked at Birmingham as both a scout and match analyst before joining Rooney at Derby and following him to DC.
It's unclear what role he will have, but he's served as a match analyst since meeting Rooney at Pride Park.
Maik Taylor
The 52-year-old former Birmingham and Millwall goalkeeper is the only remaining member of the former backroom staff.
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He made 240 appearances for the Blues and knows the club inside-out.
Plus, he has worked as a goalkeeping coach since 2013, so has years of experience.