Aircraft carrier HMS Queen Elizabeth passed through the Singapore Strait in a huge step forward for the £3.2bn warship.
The passage comes after the UK strike group took part in Exercise Konkan, which saw the Royal Navy and Indian Navy carry out a number of maritime drills.
And following the training exercise, the carrier strike group partially split as ships made their way towards the disputed South China Sea, in defiance of Beijing.
The waters have been claimed by China’s communist regime in a move that has alarmed neighbours in the region including Japan and the Philippines with illegal claims in international waters.
Foreign secretary Dominic Raab last month warned Chinese leaders the UK flotilla would be entering the South China Sea.
He told the Commons foreign affairs committee: ‘It's absolutely right we exercise and defend the rights, and we do so from the Ukrainian territorial sea to the South China Sea.’
The presence of the carrier strike group in the region follows news that Britain will permanently deploy two new patrol ships to the Indo-Pacific.
Speaking in Tokyo, defence secretary Ben Wallace said: ‘It's no secret that China shadows and challenges ships transiting international waters on very legitimate routes.
'We will respect China and we hope that China respects us ... we will sail where international law allows.'
The presence of British naval vessels in contested waters is under the microscope after HMS Defender was harassed by Russian ships and warplanes last month.
The £1bn destroyer broke off from the carrier group to sail in what international leaders say are Ukrainian waters but what Moscow insists is Russian territory, following its 2014 annexation of the Crimea.
The Kremlin claimed four bombs had been dropped into the UK vessel's path – something denied by the Ministry of Defence.
Moscow also alleged its patrol boats fired warning shots near Defender.
But British officials said a Russian maritime ‘gunnery exercise’ was taking place in the area at the time.