The 26 year-old makes the switch across the Midlands for a fee BBC Sport reports to be in excess of £2.75m.
Henri Lansbury celebrates after scoring the fifth goal for Nottingham Forest to complete his hat trick
A former student of Arsene Wenger in North London, Lansbury has spent spells with Watford, Norwich City and West Ham United, before making the move to the City Ground in 2012.
The move to Birmingham brings to an end a five-year spell with Forest, where the central midfielder scored 32 in 145 appearances for the club.
Following the sacking of Phillippe Montanier last week, Henri Lansbury now begins a new chapter in his career.
Arsenal's Henri Lansbury in action against Sheffield United's Nick Montgomery (R)
With Steve Bruce hoping to partner the Englishman with Barnsley's Conor Hourihane, as reported in The Derby Telegraph, a new look central midfield partnership will hope to see Aston Villa climb the table, with an eye on an immediate return to the Premier League.
Villa fans are delighted with the signing. Here are just a few of their comments.
Scenes if we sign Hourihane and Lansbury. I'd never have to suffer Gardner or Westwood again.— Dale (@Dale4433) January 10, 2017
Brilliant. Hopefully Lansbury will be sorted for Wolves games. @rmult— Mark Taylor (@151169) January 10, 2017
Over the last few years we have lacked goals from midfield,hopefully the arrival of Lansbury will improve that some what #avfc— Shaun Beasley (@shaunbeasley98) January 20, 2017
Genuinely chuffed with Lansbury signing, if he stays fit hes a massive player for us, heaps more passion and ability than current mids— Dalian McGuffie (@DalianMcGuffie) January 20, 2017
More than a few have reservations however about his reportedly high wages.
Whilst some Forest fans are happy to see the back of him...
I would drive Lansbury to Villa for 3 million #nffc— James Keightley (@JamesKeightley) January 10, 2017
Are you lot seriously offering lansbury 40k a week? #avfc— godfather (@Godfather19811) January 10, 2017
Have something to tell us about this article?