George I ascended the British throne as the first monarch of the House of Hanover. Although over 50 Roman Catholics were closer to his predecessor, Anne by primogeniture, the Act of Settlement 1701 prohibited Catholics from inheriting the British throne; George was Anne's closest living Protestant relative. In reaction, Jacobites attempted to depose George and replace him with Anne's Catholic half-brother, James Francis Edward Stuart, but their attempts failed.

During his reign, the powers of the monarchy diminished and Britain began a transition to the modern system of cabinet government led by a prime minister. Towards the end of his reign, actual political power was held by Robert Walpole, now recognised as Britain's first de facto prime minister. George died of a stroke on a trip to his native Hanover, where he was buried - the last British monarch to be buried outside the UK.

In the wake of the South Sea Bubble financial crisis, Walpole became First Lord of the Treasury and Chancellor of the Exchequer.

He never held the title 'Prime Minister,' but was given the powers that came to be associated with the office. George I also gave him 10 Downing Street, still the official residence of the prime minister.