In antiquity, the island bore the name Belbina and supported a town of the same name. Beyond Herodotus's passing mention, it appears occasionally in ancient sources as a piece of administrative geography — part of Attica, part of the Argolid, depending on which source and which period. A more dramatic claim attached to it for a time: some scholars proposed that Belbina should be identified as the ancient Psyttaleia, the island where Persian forces landed during the Battle of Salamis in 480 BC, and where Athenian forces subsequently trapped and destroyed them. The identification would have given Agios Georgios a starring role in one of antiquity's most consequential naval battles. The scholarly consensus, however, places ancient Psyttaleia at the island long known as Lipsokoutali and now formally renamed Psyttaleia — leaving Belbina, and by extension Agios Georgios, outside the drama. It was, as Themistocles might have said, just Belbina.

In 2016, Terna Energy completed construction of a 73 MW wind farm on Agios Georgios — the first wind farm built on a rocky islet in Greece. The installation delivers approximately 220 GWh of electricity per year to Athens, transmitted via undersea cable. The island's topography, exposed position at the mouth of the Saronic Gulf, and uninhabited status made it a practical site: no residents to consult, reliable Aegean wind, and proximity to the mainland grid. The wind turbines now define the island's silhouette as seen from passing ferries on the Athens–Hydra route. For an island that Herodotus's contemporaries considered the embodiment of provincial obscurity, it has found a quietly functional role in the modern Greek energy system.

Administratively, Agios Georgios has belonged to the municipality of Hydra since 1834 — an arrangement that made the island's wind farm revenues a matter of considerable interest to neighboring jurisdictions. In recent years, the municipality of Lavreotiki challenged Hydra's ownership of the island, and with it the associated income from the wind energy operation. The dispute went to court. In 2017, a legal judgement reaffirmed Hydra's claim. The case illustrates something persistent about small Greek islands: even the uninhabited ones can accumulate surprising economic value, and where there is value, ownership questions tend to follow. Belbina, the island that stood for insignificance in Themistocles' witticism, turned out to be worth arguing over.