The inquiry has requested the WhatsApps as evidence as part of its investigations into UK government decision-making on Covid. Hearings for that part of the inquiry are due to begin in October.
It has requested WhatsApp messages on Mr Johnson’s devices from a group chat that was set up to discuss the pandemic response.
It has also demanded his one-to-one messages exchanged during the pandemic with around 40 politicians, advisers and officials, including then-Chancellor Rishi Sunak and Simon Case, the UK’s top civil servant.
The government had attempted to block release of the raw messages, arguing that some of them were irrelevant to the inquiry and that it should be able to redact – or block out – these first before handing them over.
But it was ordered to hand over the messages unredacted earlier this month, after a legal challenge it mounted was struck down in the High Court.
Other messages the High Court ruled should be shared with the inquiry were sent on Monday morning.
Phone change
Mr Johnson was forced to change his mobile phone in 2021 after it emerged his number had been publicly available online for 15 years.
The former prime minister has insisted throughout that he is happy to share the messages on his old phone when they are accessible.
The Cabinet Office, the government department responsible for prime ministers, was ordered to hand over the WhatsApps by 16:00 BST on Monday.
The release of the messages to the inquiry does not necessarily mean the public will see them in full.
The Cabinet Office can apply to the inquiry to make redactions before they are sent to so-called core participants including other witnesses, government departments and bereaved family groups.
The inquiry could also apply its own redactions. It could also decide not to make them public at all.