Minister of State Jan O'Sullivan has been promoted to the so-called "super junior" position vacated by Willie Penrose last month.
Mr Penrose resigned as minister of state for housing over the closure of his local Army barracks in Mullingar.
Ms O'Sullivan (61), who represents Limerick City, was until today the junior minister at Tánaiste Eamon Gilmore's Department of Foreign Affairs and Trade. She was given responsibility for trade and development in March.
She will now be entitled to sit at the Cabinet table, but not participate in votes. Cabinet approved her appointment this morning.
Dublin Central backbencher Joe Costello (66) will be elevated to the Minister of State position vacated by Ms O'Sullivan. Mr Costello was Labour's director of elections in the recent presidential campaign, which resulted in the victory of Michael D Higgins. Mr Costello was also Labour’s director of elections for the Seanad campaign.
In a statement, Taoiseach Enda Kenny congratulated the new appointees.
"I look forward to working with them both in the implementation of our Programme for Government in these challenging times," he said. " I know they will both bring a wealth of experience to their Ministerial portfolios as well as great energy for the tasks which lie ahead."
Mr Gilmoe said he was "delighted" with the appointments.
Ms O’Sullivan, a former teacher, was first elected to the Dáil in 1998 in by-election brought about by the death of Jim Kemmy. She was Mayor of Limerick in 1993 and 1994. She was a member of the Democratic Socialist Party until it merged with the Labour Party.
She is married to Paul O'Sullivan. They have one son Paddy and one daughter Emily. She was educated at Trinity College, Dublin and University College Cork.
