Quique Setien was relieved of his duties in the wake of Barca’s humiliating 8-2 defeat to Bayern Munich in the Champions League and Koeman was officially named as his successor on Wednesday morning.
The 57-year-old, previously manager of Southampton and Everton, played for the Catalan giants between 1989 and 1985 and has made no secret of his ambitions to return to the Nou Camp in recent years.
It means the Netherlands will have to find a replacement ahead of next summer’s Euros after Koeman led the team to a second-place finish behind Germany in qualifying Group C.
Koeman took over the national side in February 2018 following the resignation of Dick Advocaat.
Reacting to the news, Netherlands and Liverpool centre-back Van Dijk posted on Twitter: ‘I want to congratulate Ronald Koeman on his move to Barcelona.
‘The Netherlands are losing an experienced and successful coach. But there remains that special bond remains between us.
‘He brought me to the Premier League and gave me the Netherlands’ captaincy.
‘I understand he wants to live up to his dream. Recent world events and his personal life have certainly played a role in this. Best of luck!’
Josep Maria Bartomeu claims Koeman was the first man Barcelona approached when they began the process of finding a potential successor to Setien.
‘We bet on Koeman because of his experience of the Barca style and that he believes in the Barca philosophy,’ the Barca president said.
‘In December we spoke with different coaches to see who could come. Koeman told us that he had a responsibility with the Netherlands and could not leave them without a coach, but he was the first coach we contacted.
‘It has been a dream for him for a long time.’