Heraclius was able, after centuries of Iranian suzerainty over Georgia, to guarantee the autonomy over his kingdom throughout the chaos that had erupted following Nader Shah's death. He became the new Georgian king of a politically united eastern Georgia for the first time in three centuries. Though Heraclius tendered his de jure submission to the newly established Zand dynasty quickly after the unification in 1762, the kingdom remained de facto autonomous for the next three decades to come. In 1783, Heraclius signed the Treaty of Georgievsk with the Russian Empire, by which he formally laid Kartli-Kakheti's investiture in the hands of the Russian monarch, and made the kingdom a Russian protectorate. Amongst others, this provided the nominal guarantee for protection against new Iranian attempts, or by any others, to (re)conquer or attack eastern Georgia. By the 1790s, a new strong Iranian dynasty, the Qajar dynasty, had emerged under Agha Mohammad Khan Qajar, which would prove pivotal in the history of the short-lived kingdom.
In the next few years, having secured mainland Iran, the new Iranian king set out to reconquer the Caucasus and to re-impose its traditional suzerainty over the region. After Heraclius II refused to denounce the treaty with Russia and to voluntarily reaccept Iran's suzerainty in return for peace and prosperity for his kingdom, Agha Mohammad Khan invaded Kartli-Kakheti, captured and sacked Tbilisi, effectively bringing it back under Iranian control. This was short-lived, however, for Agha Mohammad Khan was assassinated two years later. Heraclius II himself died a year after that.
The following years which were spent in muddling and confusion, culminated in 1801 with the official annexation of the kingdom by Alexander I within the Russian Empire during the nominal ascension of Heraclius's son George XII to the Kartli-Kakhetian throne. Following the Russo-Persian War of 1804-1813, Iran officially ceded the kingdom to Russia, marking the start of a Russian-centred chapter in Georgian history.
After Nader Shah's death in 1747, Heraclius II and Teimuraz II capitalized on the eruption of chaos in mainland Iran. In the ensuing period Heraclius II made alliances with the khans of the area, established a leading position in the southern Caucasus, and requested Russian aid. In 1762, he succeeded his father as king of Kartli, and with already being king of Kakheti, eastern Georgia thus became politically unified for the first time in three centuries. Around 1760, at about the time Heraclius II proclaimed the kingdom, it had become evident as well that Karim Khan Zand had become the new dominant Iranian ruler, at least for the time being. In 1762-1763, during Karim Khan's campaigns in Azerbaijan, Heraclius II tendered his de jure submission to him and received his investiture as vali ("governor", "viceroy") of Gorjestan (Georgia), the traditional Safavid office, which by this time however had become an "empty honorific". Karim Khan died in 1779 however, with Persia again being engulfed into chaos.
Seeking to remain independent, but also realizing that he would need a foreign protector with regard to his kingdom's foreign policy, King Heraclius II concluded the Treaty of Georgievsk with Russia in 1783, resulting in the transfer of responsibility for defense and foreign affairs in the eastern kingdom, as well as importantly, officially abjuring any dependence on Iran or any other power. However, despite these large concessions made to Russia, Heraclius II was successful in retaining internal autonomy in his kingdom.
Heraclius II's "curiously ambivalent position" in these decades is reflected in the coins issued by him in his realm. Silver coins were struck with the name of Ismail III on it, or with the Zand-style inscription ya karim ("O Gracious One"), whereby an eptithet to God was invoked, which actually referred to Karim Khan Zand. These coins were minted in Tbilisi up until 1799 – some twenty years after Karim Khan Zand's death. In the same decades, the copper coins struck at Tbilisi bore three types of iconography; Christian, Georgian, "and even" Imperial Russian (such as the double-headed eagle). By minting the silver coins with a reference to Karim Khan Zand on it they were usable for trade in Iran, whereas the copper coins, struck for only local use, reflected Heraclius II's political orientation towards Russia.
While Heraclius II's court maintained a certain Persian-type pomp, and he himself dressed in the Persian style as well, he launched an ambitious program of "Europeanization" which was supported by the Georgian intellectual élites; it was not overwhelmingly successful however, because Georgia remained physically isolated from Europe and had to expend all available resources on defending its precarious independence. He strove to enlist the support of European powers, and to attract Western scientists and technicians to give his country the benefit of the latest military and industrial techniques. His style of governing resembled that of contemporary enlightened despots in Central Europe. He exercised executive, legislative, and judicial authority and closely supervised the activities of government departments. Heraclius’s primary objective in internal policy was to further centralize the government through reducing the powers of the aristocracy. For this purpose, he attempted to create a governing élite composed of his own agents to replace the self-minded aristocratic lords in local affairs.