It was feared the machine had been lost to the depths as a previous attempt to raise it from the wreck site off the coast of Co Cork last summer ended in failure when a lift bag punctured.
Heritage Minister Heather Humphreys said the telegraph had been relocated by recreational divers, who marked its position on the seabed.
The telegraph was brought to the surface in good condition on Tuesday under the supervision of an archaeologist from the Department’s National Monuments Service (NMS).
The Lusitania, a Cunard British cruise liner that was the largest ship in the world when built, was torpedoed by a German U-boat off the coast of Co Cork on May 7, 1915, with the loss of 1,201 lives. It was en route from New York to Liverpool.
Its wreck, 11 nautical miles off the Old Head of Kinsale, is regarded as a war grave and protected by an Underwater Heritage Order under the National Monuments Acts.
US businessman Gregg Bemis owns the wreck.
Ms Humphreys said: “I am happy to confirm that this important piece of the Lusitania has now been recovered from the wreck off the west Cork coast. I understand that the telegraph is undamaged and in excellent condition.
“I also understand that the owner of wreck, Gregg Bemis, intends to place the telegraph, and the pedestal successfully recovered last year, on display in a local museum, along with other artefacts he has recovered during earlier dives, which is great news for the local community.”
Among the liner’s 1,266 passengers and 696 crew, there were 129 children, of whom 94 died as the ship, sailing from New York, sank in just 18 minutes.
The cause of a second explosion on the ship, after the torpedo struck, remains a mystery.
Built at the John Brown shipyard on the River Clyde in Scotland, the Lusitania was carrying 159 Americans, of whom 128 were killed. Its sinking has been cited as factor in the US’ eventual entry into the First World War.
The ship’s captain, William Turner, who survived after the ship went down, had received messages on the morning of the disaster that there were German submarines in the area and he altered course
Separately, the largest remaining panel fragment from the first-class lounge of the Titanic will return to Britain for the first time since the ship sailed from Southampton in 1912 for a major new exhibition about the history of ocean liners.
It will be one of more than 250 objects, including paintings, sculptures and ship models, that will go on display at the V&A’s Ocean Liners: Speed & Style exhibition next year.
The wooden panel, which comes from where the Titanic broke in half as it sank, was found floating on the surface of the Atlantic .