The 23-year-old joined Villa on a five-year contract for an undisclosed fee, believed to be in the region of £12m, after successfully completing his medical at Bodymoor Heath.
Ayew joins fellow former Ligue 1 players Jordan Amavi and Idrissa Gueye at Villa Park and could find himself playing against brother Andre, who signed for Swansea over the summer.
The former Marseille striker, who scored 12 goals in 26 league appearances for Lorient last season and has played 28 times for Ghana, will be a direct replacement for Christian Benteke after he moved to Liverpool for £32.5m.
“I’m really pleased to bring Jordan to the football club,” Villa boss Tim Sherwood told the club’s official website.
“He is a fantastic young player who is perfectly suited to the Premier League.”
Ayew himself is delighted to have sealed his move to the English top-flight and revealed it took him just 10 seconds to make up his mind about joining Villa.
“When I spoke to the coach I knew this was the place for me. He has so much enthusiasm and determination for the game of football,” he said.
“It took 10 seconds to work out he was the right coach for me and Aston Villa was the right team.
“I am the happiest man in the world. It’s one of my greatest days in football.
“My dream was to play for a big team in England – and Aston Villa is undoubtedly one of the greats in English football.”