Downing relishing Reds challenge
The 26-year-old, who has been capped 27 times, became Kenny Dalglish's fourth summer signing following the transfers of Jordan Henderson from Sunderland, Charlie Adam from Blackpool and Doni from Roma.
Villa confirmed earlier this week that Downing had submitted a formal transfer request, and he travelled to Liverpool to discuss terms and complete a medical before signing a long-term deal at the club.
The former Middlesbrough man, who moved to Villa Park for around £10m two years ago, had been a prime summer target of Dalglish, who saw bids of £12m and £15m rejected before an agreement for an undisclosed fee - believed to be in the region of £20m - was struck.
Downing made it clear only last month, when on England duty, that he would not sign an extension with Villa, effectively forcing them to listen to offers. Arsenal were reported last weekend to have joined the competition for his signature, but Liverpool were always the frontrunners, according to the player himself.
He said: "It's a great feeling and I'm very happy to be here. It's been a long time coming and I've had to wait a few weeks, but I'm really pleased to be here. With the tradition, the manager and the players they have here, there was a big temptation to come here, and once I knew of their interest, there was only one place I wanted to go.
"It will be a great feeling to run out at Anfield. It's always nice to come and play here. The atmosphere is always great and the fans are brilliant. When I wanted to come to Liverpool, it was the first thing I thought of: playing at Anfield in front of those great fans. I'm really looking forward to it."
Comolli pleased with Doni arrival
Downing's arrival marked the end of a busy day for Liverpool, who also completed the signing of Doni. The 31-year-old Brazilian is thought to have joined on a free transfer after agreeing personal terms and passing a medical.
Liverpool director of football Damien Comolli said: "We are delighted to sign Doni. It's a position we felt we had to strengthen, because it will allow our young goalkeepers to go on loan and get some experience at some point during the season, which is crucial in their development."