The 26-year-old midfielder - younger brother of Chelsea's Eden - has signed a five-year deal for a reported £30m.

Germany midfielder Julian Brandt has also signed for Dortmund, from Bayer Leverkusen, on a five-year deal.

Lucien Favre's side finished as runners-up in Bundesliga, two points behind champions Bayern Munich.

Hazard scored 10 goals and registered 12 assists as Monchengladbach finished fifth in the league.

"Now was exactly the right time to take the next step in my career," he said.

A former Chelsea youth player, Hazard spent five years at Monchengladbach. He has won 21 caps for Belgium and was part of the squad that finished third at last year's World Cup.

His form this season had seen him linked with a move to Liverpool and Arsenal.

Dortmund sporting director Michael Zorc said: "He has consistently demonstrated his class over the course of the past few years."

Brandt, 23, made 43 appearances for Leverkusen last season, scoring 10 goals.

"I am a person who sometimes decides things from the gut and for whom a good feeling is important," Brandt told the club website. "In the case of Borussia Dortmund, I have a very good feeling.

"One of the main reasons for my change is that BVB narrowly missed the title last season, so there is room for improvement."