The 24-year-old Belgian will replace fellow-countryman Jason Denayer at the heart of the champions’ defence after he returned to the Etihad following a season-long loan deal at Parkhead.
Boyata, who has had two seasons on loan at Bolton and FC Twente since joining City from FC Brussels in July 2009, figured in just two league games for Manuel Pellegrini’s side last season.
In a statement on Celtic’s website, the club said: “Celtic are delighted to announce the signing of Belgian international Dedryck Boyata.
“The 24-year-old defender becomes manager Ronny Deila’s first signing of the close season and will join up with his new team-mates later this month when they report back for pre-season training ahead of the UEFA Champions League qualifiers.”
And speaking exclusively to Celtic TV after signing his contract, Boyata, who will wear No 20, said: “It feels really good. Celtic are a very big club and it feels good to be part of it.
“The manager came to see me in Manchester and I spoke to him about having me here and all the ideas he had for me playing for the team.
“So I was very pleased with his plans and from that point I thought that moving to Glasgow would be a good idea and we tried to do everything right for me to move here.”