The vessel was deployed to the region at the beginning of May.
The Irish naval vessel the LÉ Róisín has rescued 125 refugees off the coast of Libya.
It is the first successful mission the crew has undertaken since being deployed at the start of this month.
107 men and 18 women were rescued from an inflatable craft, around 40 nautical miles north-east of Tripoli.
This evening, 240 additional people also boarded the LÉ Róisín.
The Irish ship assisted the Italian Naval Vessel ITS Commandante Borsini, with the refugees & migrants transferring to the Róisín.
The LÉ Róisín is now travelling to an unspecified 'port of safety' in Sicily with 365 people on board.
Minister of State for Defence Paul Kehoe has commended the officers involved for their 'outstanding work' today.
The 60-strong crew of the LÉ Róisín are assisting Italian authorities in the search and rescue activities involving migrants and refugees.
More than 8,000 people were rescued by the Irish navy in the Mediterranean last year.
International operations are continuing in the region, and over 500 people have died attempting to cross the Mediterranean so far this year.
The International Organisation for Migration (IOM) confirmed that 531 people are lost or missing.
The Immigrant Council of Ireland says the operation is reminder that "Ireland must keep its response to the refugee crisis under constant review.
"The crisis is far from over and the need for search and rescue on the long and dangerous crossing from Libya to Italy remains great," the council added.