The £3.2bn ship is leading the UK Carrier Strike Group – the Royal Navy's largest deployment in more than a decade.
The Royal Navy's flagship had been expected to complete her pre-deployment preparations at anchor in the Solent following Exercise Strike Warrior off the coast of Scotland, but poor weather forecasts mean this was done alongside in Portsmouth instead.
The vessel and her Carrier Strike Group are now heading south through the Atlantic with a stop-off expected in Gibraltar before heading into the Mediterranean.
The group will visit more than a fifth of the world's nations over 28 weeks.
It is the aircraft carrier's maiden operational deployment.
One thousand seven hundred personnel will be living and working on board HMS Queen Elizabeth, 250 of those are from the US.
Joining the aircraft carrier are six frigates and destroyers, two Royal Fleet Auxiliary support ships, an Astute-class submarine, 18 F-35 fighter jets and 14 naval helicopters which arrived this week ahead of deployment.
What Forms A Carrier Strike Group?
Protecting an aircraft carrier is a large-scale task.
Carrier Strike Groups escort in the form of Type 23 frigates, which have anti-submarine capabilities, and Type 45 destroyers with sophisticated air defence systems.
Astute-Class submarines can use advanced sensors to generate a clear picture of the environment surrounding the force, feeding intelligence through to other vessels from beneath the surface.
For her 2021 deployment, Queen Elizabeth will embark F-35Bs and Royal Navy Merlin helicopters.
The carrier will be escorted by Royal Navy Type 45 destroyers, Type 23 frigates and Royal Fleet Auxiliary support ships.
The Carrier Strike Group can cover 500 nautical miles in just one day and is capable of tracking up to 1,000 targets from 400km away.
Alongside these other vessels, the aircraft carrier will also need a replenishment ship, provided by the Royal Fleet Auxiliary.
This would contain all weaponry needs, as well as food for the sailors.
In 2018, RFA Fort Rosalie delivered vital supplies to the aircraft carrier USS Theodore Roosevelt in the Arabian Gulf.
Fort Rosalie transferred 96 pallets of stores to the Roosevelt as part of her tasking with the aircraft carrier's strike group.
British personnel from RFA Fort Rosalie joined the US strike group in the Gulf.
They used the trip to see first-hand how operations are conducted aboard a US vessel, ahead of the RFA supporting the aircraft carrier HMS Queen Elizabeth.
The Queen Elizabeth-class ships will call on other vessels to support them, although it is unlikely both carriers will be deployed on operations simultaneously.
Each aircraft carrier can be deployed with up to two operational Lightning squadrons and 24 F-35Bs on board, although the maximum capacity allows for up to 36.
Each squadron will consist of about 12 aircraft, although for the majority of the time there could be as a few as 10 jets on board at once.
Each Carrier Strike Group will likely include Type 45 destroyers, Type 23 frigates, Royal Fleet Auxiliary ships, an Astute-class submarine and, in the longer term, Type 26 frigates.
Cover image: HMS Kent and HMS Queen Elizabeth together during training at sea (Picture: Royal Navy).