The 30-year-old moves to the West Midlands after his contract at Norwich had expired and with veteran Villa goalkeeper Shay Given understood to be on the brink of joining Premier League rivals Stoke.
"I'm delighted to find myself working with Tony Parks again as he was the goalkeeping coach at Norwich City so he knows me really well," Bunn told the official Villa website.
"Aston Villa is a huge football club and this was too good an opportunity to miss out on.
"I'm looking forward to getting to know my new team-mates over in Portugal at our pre-season training camp and I can't wait to get started."
Bunn started his professional career at Northampton before moving on to Blackburn and also enjoying loan spells at Leicester and Sheffield United.
He joined Norwich in 2012 and went on to make 31 appearances for the Canaries.
Source : PA
Source: PA