the Duo will "redefine the experience of using a foldable phone".
Apple unveiled its first foldable iPhone, called Duo, at the company’s annual launch event in California.
The device is the most expensive iPhone to date, with a starting price of $1,999 (£1,476).
Roughly the size of a passport when closed, the phone opens to reveal a 7.6in (19.3cm) screen, the largest ever on an iPhone.
It also allows users to use an Apple Pencil on the device, a capability previously reserved for iPad users.
The Duo allows users to split the screen between two different apps or use two windows of the same website, such as when comparing products while shopping online.
Apple’s new foldable iPhone will be available from October 23.
John Ternus, Apple’s new CEO, formally took over from Tim Cook on September 1 and unveiled the device at the company’s headquarters in Cupertino.
He said the Duo will “redefine the experience of using a foldable phone”.
The iPhone 18 Pro and iPhone 18 Pro Max were also unveiled at the launch event.
The iPhone 18 Pro can be pre-ordered from September 12 and starts at $1,199 (£885), while the iPhone 18 Pro Max starts at $1,299 (£959).
Apple said the new models feature longer battery life and faster charging, with the Pro Max offering up to 45 hours of video playback.
The company also highlighted new camera features, including “cinematic effects” from regular video captured on the phone.
Users will also have new options for manual controls and “smart focus tracking”, which allows them to focus on a single moving subject.
Other devices revealed at the event included new AirPods headphones and a new model of Apple Watch.
Apple is not the first company to develop a foldable smartphone, with rivals including Samsung, Motorola and Google having already released their own devices.
Forrester analyst Dipanjan Chatterjee said Apple’s decision to release a foldable phone after its competitors was “straight out of Apple’s playbook”.
He explained that this involved waiting for the product to “work out its kinks” and for the market to “offer glimpses of viability”.
Ben Wood, chief analyst at CCS Insight, said the Duo was “always going to eclipse Apple’s other announcements”.
He added that the device marks Apple’s entry into the “niche foldable smartphone category”.
Mr Wood said there is certain to be demand for the Duo, which costs less than some analysts had anticipated.
However, he noted that foldable models still account for less than 5% of the overall smartphone market.
The launch comes after Apple unveiled advances in artificial intelligence earlier this year, including upgrades to its Siri assistant.
The company has also emphasised privacy and day-to-day use as it attempts to catch up with rivals in AI.
In June, it was reported that millions of UK Apple customers are set to be included in a class action lawsuit against the technology giant over its iCloud storage system.
If successful, the £3 billion lawsuit could see around 39.7 million people receive compensation.
