visionOS is a mixed reality operating system derived primarily from iPadOS and its core frameworks (including UIKit, SwiftUI, ARKit and RealityKit), and MR-specific frameworks for foveated rendering and real-time interaction. It was developed by Apple exclusively for its Apple Vision Pro mixed reality headset. It was unveiled on June 5, 2023, at Apple's WWDC23 event alongside the reveal of the Apple Vision Pro. The software released on February 2, 2024, shipping with the Apple Vision Pro.

Apple has reportedly been working on and conceptualizing visionOS throughout the 2010s and early 2020s. Internally codenamed Borealis, it was officially revealed to the public at Apple's WWDC23 event alongside the Vision Pro. Apple stated the two would release in early 2024. App Store guidelines for the operating system similarly state that developers should refer to visionOS software as "spatial computing experiences" or "vision apps", and avoid the use of terms such as "augmented reality" and "mixed reality".

During the event, The Walt Disney Company announced plans to develop spatial computing apps for visionOS; Disney+ currently offers features such as streaming of selected titles in stereoscopic 3D, and they also offer 3D environments based on the El Capitan Theatre and locations from Disney-owned franchises.

The operating system was initially planned to be released as xrOS before the name was changed reportedly days before its announcement, after the WWDC23 keynote and developer sessions had already been filmed. References to xrOS are still present throughout visionOS development materials. On January 8, 2024, Apple announced that the Vision Pro with visionOS would be available in the US on February 2, 2024, with pre-orders beginning on January 19.

From June 5–12, 2023, Apple released 35 free virtual sessions covering visionOS development as part of WWDC23. On June 21, 2023, Apple released Xcode 15 Beta 2, which was the first Xcode beta to include a software development kit for visionOS and Reality Composer Pro, a tool to create 3D content for visionOS. Xcode 15 launched without these features, which were eventually added in Xcode 15.2 on January 8, 2024, the same day that Apple started accepting submissions for the visionOS App Store.

During the WWDC23 keynote, Apple revealed it was working with Unity Technologies to support the Unity engine on visionOS, and that Unity would be releasing development tools for 3D games on Vision Pro, which launched in beta on July 19, 2023.

visionOS uses a 3D user interface navigated via finger tracking, eye tracking, and speech recognition. For example, the user can click an element by looking at it and pinching two fingers together, move the element by moving their pinched fingers, and scroll by flicking their wrist. Apps are displayed in floating windows that can be arranged in 3D space. Text input is via a virtual keyboard, the Siri virtual assistant, and external Bluetooth peripherals including Magic Keyboard, Magic Trackpad, and gamepads.

During visionOS setup, a user can create a digital persona by taking off the headset and scanning their face with it. Users can use this persona during FaceTime calls, and see other participants' personas if they are using visionOS. From visionOS 1.1, the ability to see personas in 3D moving around and interacting with apps was added, dubbed 'Spatial Personas.'