Puerto San Julián was discovered by Ferdinand Magellan in 1520, and the first mass in Argentine territory was celebrated there on the 1st April that same year.
In 1578 sought land the English corsair Drake, who had left from Plymouth on 13th December 1577 in the most hermetic secret with a fleet of five ships and 162 crew members. Secrecy was due to the fact that England was in good relations with Spain and Drake's purpose was precisely to assault Spanish ships, as well as Portuguese ones if found, and take possession of all valuable things they could. On 21st June, they disembarked in Puerto San Julián without the caravel Christopher, which had burnt. They decided to stay there during the winter, where Magellan had done so fifty-eight years before, and as had occurred on that occasion, somebody paid insubordination with his life. Thomas Doughty was executed, and on 20th August the ships crossed the strait and sailed into the Pacific.
In 1741 the English Admiralty sent to the southern seas a fleet integrated by 7 ships with 250 canyons, and almost 2000 marines commanded by the temerarious George Anson. Since Spain and England were at war, the British crown found no impediment to occupy Spanish possessions, board and kidnap all valuable shipment. But this enterprise would not be lucky in spite of being blocked by another small Spanish fleet, since a very hard tempest destroyed both ships, and neutralized their actions.
On 23rd March 1780 arrived at San Julián a colonizing crew directed by Antonio de Viedma with the intention of settling and fortifying the place, but the winds and the search for drinking water supplies lead them to Deseado, where they had to spend the winter.
In 1752, Domingo Basavilbaso, an important merchant from Buenos Aires extracted salt from San Julián in Cabo Curioso, and sold it in Buenos Aires. Those were prosperous times for this activity, since British sea lions and whales’ hunters frequented these coasts and nobody worried about the Spanish vigilance, which was not very strict.
In 1780, by order of viceroy Vértiz, and given the Spanish politics for founding villages to defend the Atlantic coast, they found a village with the name Nueva Colonia de Florida Blanca, 10 kilometers to the north west from the present location of Puerto San Julián, on 1st November that same year, for what they recruited 200 families to build the new village, but the place was abandoned in January 1784, since Viceroy Vértiz did not agree to maintain any village which was not self-supplied.
Finally it was founded as Puerto San Julián on 17th September 1901, and declared historical site by decree 12.466 of 5th November 1943.