Kevin Toland will become CEO of the food group, Aryzta
The daa, formerly the Dublin Airport Authority, is to begin a search for a new chief executive.
Kevin Toland has announced he is leaving the role to become CEO of Aryzta, the publicly quoted food group.
Mr Toland, who became daa chief executive in January 2013, will join Aryzta following a six-month notice period - or earlier if agreed.
DAA chairman, Pádraig Ó Ríordáin, said it had been "a privilege to work with Kevin" over the past four and a half years.
"Under Kevin's leadership, Dublin Airport was the fastest-growing major airport in Europe last year, Cork Airport is back to robust growth and our international businesses have expanded strongly."
The board of daa will now begin the process of finding a new chief executive, Mr Ó Ríordáin added.
On his departure, Mr Toland said: "It has been an absolute honour to lead daa, and I will remain fully focused on the business in the months ahead.
"I have greatly enjoyed working with staff and management.
"I have learned so much from my time with daa and am so proud of the fantastic job that our staff do for our customers and passengers across the globe on a daily basis."
The daa operates Dublin and Cork Airports, and also owns the international travel retail business ARI - which has operations in 10 countries.