The Taoiseach Mr Ahern will address the Welsh Assembly tomorrow.
A Welsh Assembly spokeswoman said the visit had been arranged to further strengthen the friendship between Wales and Ireland.
The Taoiseach will hold meetings with First Minister Rhodri Morgan, Welsh Secretary Paul Murphy, Assembly Presiding Officer Lord Dafydd Elis-Thomas and Foreign Office Minister Brian Wilson before addressing Assembly members.
Mr Ahern will also attend two events in Newport, south Wales, aimed at boosting Wales' international profile.
Mr Morgan welcomed the visit, which takes place on St David's Day.
"I am delighted the Taoiseach will be visiting Wales on our special day when we remember our patron saint," he said.
"We share so much in common with Ireland and cast envious glances at the way in which the country has developed one of the fastest growing economies in Europe.
"Objective One funding from Europe gives us the opportunity to emulate our Celtic cousins and it is highly significant that as well as addressing the Assembly the Taoiseach will be participating in the launch of two important events to show what Wales can offer the world."
The visit will follow Mr Ahern's talks with Prime Minister Tony Blair in London tonight on the Northern Ireland peace process.
PA
