The Egyptian, who has put pen to paper on a three-year deal, left Hull's training camp in Portugal on Monday after Villa triggered his release clause in his contract
He becomes the third new signing at Villa Park this summer following the arrivals of John Terry and Sam Johnstone from Chelsea and Manchester United respectively
Elmohamady told the club's official website: "I am delighted to be here at Aston Villa
"Aston Villa is a great club and I am thrilled to join - it's one of the very biggest clubs in England and its history and tradition is there for all to see
It's a great time to join too as we look for promotion to the Premier League
"I will give absolutely everything to help us achieve that goal
I know, first hand, what it takes to win promotion and I want that feeling again."
It is the third time Steve Bruce has signed the 29-year-old having also acquired him while manager at Hull and Sunderland
Elmohamady was an integral part of Bruce's previous two promotion-winning teams at Hull
Elmohamady initially joined the Tigers on loan from Sunderland in August 2012 and went on to make 218 appearances for the club, scoring 12 goals
Source : PA
Source: PA