In 2020, King won twelve out of sixteen races in the Porsche Carrera Cup Great Britain, to take the series title with a round to spare.

[1] The following season, King won both the National Open – giving him the "O" plate in recognition – and overall championship titles in the F6 Cadets class.

King also made a one-off appearance in the Ginetta G40 Cup as a guest driver, where he won all three races at Brands Hatch.

[22] In November 2019, King was announced as the Porsche Carrera Cup GB Junior driver for the 2020 and 2021 seasons,[23] and he signed a contract with Team Parker Racing in February 2020.

[24] The championship start was delayed from the end of March to the start of August due to the COVID-19 pandemic in the United Kingdom; at the season-opening meeting at Donington Park, King took pole position by two tenths of a second, and was leading the opening race of the weekend before clipping a tyre wall at the final chicane.

In the second race – with a partially-reversed grid – King started third but led by the end of the first lap, and ultimately went on to claim his first win in the series.

[25] King swept the races at Brands Hatch and Oulton Park, before his five-race win streak was ended at Knockhill, after he was forced to retire with a coolant leak.