Independent News and Media chief executive Michael Doorly has stepped down from his role, with long-time Mediahuis executive Marc Vangeel taking over.
Mr Doorly announced his resignation to staff yesterday.
On Tuesday, the High Court approved the takeover of INM, which publishes the Herald, by the Belgium-headquartered Mediahuis.
"This is indeed a historical day for INM and, in many ways, the end of an era, but most importantly, the start of an exciting new chapter for the company," Mr Doorly told staff.
"This is a time for change and INM will benefit from its membership of the larger Mediahuis Group as it accelerates its digital transformation programme.
"On a personal level, it has been an immense privilege to have been CEO of INM and to have worked with such a variety of talented people in so many different disciplines.
"We should be proud that INM is the leading media publisher on the island of Ireland which, it should be noted, was a key factor for Mediahuis in acquiring the company."
New CEO Marc Vangeel is the former chief executive of Mediahuis-owned Telegraaf Media Groep.
In addition, Peter Vandermeersch has been appointed to the role of publisher at INM, where he will now be responsible for the long-term strategy of INM's titles.
INM managing director of publishing, Richard McClean, will assume the role of chief operating officer.
The management changes were confirmed as INM announced to the stock market that the scheme of arrangement to buy the plc had become effective from yesterday.
Dispatch of cheques to shareholders is expected to happen on August 9 and by no later than August 14.
Mr Doorly said he would be on hand to assist with the transition.
For the first time in the history of Mediahuis, it will be active outside its home markets Belgium and the Netherlands and enter the English-language media market.