The 20-year-old centre-back has signed a three-year contract and will join the Premier League club’s development squad.
Harries told his new club’s website: “I am delighted to be here. It is a little hard to leave Coventry, but I am really looking forward to getting going at Swansea.
“My aim in the long term is to play in the Premier League. If I am lucky enough and good enough for the manager to trust me at some stage in the future, that would be a dream come true.”
Harries progressed through Coventry’s academy and made his first-team debut on the final day of the 2015-16 season.
He made a total of 17 appearances for the Sky Blues as they were relegated from Sky Bet League One last season.
Derek McInnes wants his Aberdeen players to dare to dream as they look to grab their first win in 10 attempts against Celtic.
Brendan Rodgers is looking for Celtic to move on from their Europa League exit when they return to Ladbrokes Premiership action at Aberdeen on Sunday.