The Lé Eithne located and rescued 367 migrants from a wooden barge off the coast of Libya on Monday.
The Irish naval vessel came to the aid of those on the barge which was foundering in choppy waters about 50kms from Tripoli.
The operation started at 7.25am and ended two-and-a-half hours later at 10.09am.
There are now 278 male, 80 female and 9 children on board the Lé Eithne where they will receive medical screening, food and water.
The Lé Eithne was dispatched to the Mediterranean in May from Naval Service Headquarters in Haulbowline, Cork to assist the Italian authorities in the humanitarian search and rescue operations in the Mediterranean.
The vessel will be deployed in the Mediterranean for a period of up to six months, subject to the operational demands and requirements arising in the theatre of operations.
To date it has rescued almost 1,500 migrants from a variety of small vessels, including barges, small fishing craft and inflatable dinghies. The Irish Naval Service vessel has a crew of 67 plus two Army medics.
It is the second time in a week the Lé Eithne has rescued migrants from the Mediterranean Sea.
On June 8th it rescued 399 migrants from north Africa. The migrants were transferred to the care of the Italian authorities in Taranto, a port city in the heel of Italy.
The Lé Eithne is now awaiting direction from the Italian Maritime Rescue Co-Ordination Centre for its next task.