Hertha announced last week that manager Pal Dardai will stand down from his position in the summer, with Ante Covic set to take over as his replacement.
And the Croatian sees Boyata become the club’s first signing since his announcement as boss, as he begins masterminding an improvement on Hertha’s 11th-place finish this term.
Hertha director of sport Michael Preetz said: “We have been tracking Dedryck for a while and are fully convinced of his quality. We are sure that he will strengthen our defence.”
The 28-year-old came through the youth ranks at Manchester City after joining the club’s academy in 2007, signing a first professional contract in 2009 and making a Premier League debut in 2010.
Following loan spells at Bolton and FC Twente in the Netherlands, he left the Etihad to join the Hoops in 2015, where his domestic and European performances helped cement his reputation as a dependable defender.
He also starred for Celtic in the Champions League during their group-stage campaigns in 2015 and 2016.
This season, Boyata has helped Celtic wrap up an eighth successive Scottish Premiership title while victory in the Scottish Cup final next week would secure an unprecedented third successive Scottish domestic treble.
“I am pleased that the deal has worked out,” said Boyata. “It is an ambitious club and we have similar goals. Also, I was very impressed with Michael Preetz’ efforts to bring me here.
“I am looking forward to the new season and want to achieve something with the club.”
Meanwhile, Celtic are yet to announce their managerial plans for next season, with Neil Lennon still currently in caretaker charge following the departure of Brendan Rodgers to Leicester.
Lennon is believed to be the favourite to land the job permanently after he finished Rodgers’ work in wrapping up the Premiership title.