Apple has released watchOS 27, bringing some of the biggest changes to the Apple Watch in recent years. The update introduces Siri AI, a smarter and more conversational Siri experience, along with a dedicated Siri app that lets you revisit previous conversations and start new ones right from your wrist.

Moreover, the Workout Buddy now works independently of the iPhone, the new dynamic app grid makes it easier to find your most-used apps, and a new single-tap gesture lets you interact with Smart Stack widgets using one hand. watchOS 27 also expanded Cycle Tracking support for perimenopause and menopause.

If you have a compatible Apple Watch, there is plenty to explore in watchOS 27. But before you install it, you should first check whether your Watch and paired iPhone meet Apple’s requirements. Here’s everything you need to know about watchOS 27 compatibility and how to update your Apple Watch.

Is your Apple Watch compatible with watchOS 27?

While Apple typically provides 5 years of software updates for Apple Watch, watchOS 27 no longer supports the Apple Watch Series 8, Series 7, Series 6, first-generation Ultra, or second-generation SE.

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Here’s a complete list of Apple Watch models that support watchOS 27:

Apple Watch Series 12
Apple Watch Series 11
Apple Watch Series 10
Apple Watch Series 9
Apple Watch Ultra 4
Apple Watch Ultra 3
Apple Watch Ultra 2
Apple Watch SE 3

So, if you have an Apple Watch Series 8 or older, you cannot install watchOS 27. Your Watch will remain on the latest version supported by that model.

What iPhone do you need for watchOS 27?

There is another important requirement that is easy to overlook.

To update to watchOS 27, you need:

iPhone 11 or later, or
iPhone SE (2nd generation or later)
Updated to iOS 27 or later

This means simply owning a compatible Apple Watch isn’t enough. Your paired iPhone must also meet Apple’s requirements.

Requirements to install watchOS 27

Before I start any Apple Watch update, I prefer to get everything ready first. It saves a lot of frustration if the update takes longer than expected.

Here’s what you should check:

Update your iPhone to the latest iOS 27 or later.
Ensure the battery is at least 50% on both the iPhone and the Apple Watch.
Connect your iPhone and Apple Watch to a Wi-Fi network.
Keep your Apple Watch within the connection range of your iPhone to prevent disconnection.
Place the Apple Watch on its charger before starting the installation.
Make sure you have enough free storage on the Apple Watch for the update.

Do you need your iPhone to update watchOS 27?

Not necessarily.

Apple allows compatible Apple Watch models to download and install watchOS updates directly from the Watch itself. However, the Watch still needs to meet Apple’s compatibility requirements, and using the paired iPhone remains the more convenient option for many users.

How to update Apple Watch directly

One of the easiest things about recent watchOS versions is that I don’t always need to reach for my iPhone to start an update.

If your Apple Watch is connected to Wi-Fi, you can update it directly.

Follow these steps:

Open Settings on your Apple Watch.
Scroll down and tap General.
Navigate to Software Update.
Wait while your Apple Watch checks for an available update.
If an update is available, tap Download and Install.
Tap Proceed. Enter your Apple Watch passcode if prompted.
The Apple Watch will restart once the update is installed.

The installation can take some time, so I wouldn’t start the update right before leaving home or heading to work.

How to update Apple Watch with your paired iPhone

For most people, updating through the iPhone is probably the simplest method. Whenever an Apple Watch update is available, your paired iPhone will notify you.

If you intend to update through the iPhone, follow these steps:

Open the Watch app on your iPhone.
Make sure your iPhone and Apple Watch are connected to Wi-Fi.
Tap General and select Software Update.
Wait for the iPhone to check for available watchOS updates.
On the next page, tap Download and Install Now.
Enter your iPhone passcode.
Read the terms and conditions. Once you’ve read the terms and wish to proceed, tap Agree.
You might be asked to enter the Apple Watch passcode; once you do, the update process will begin.
A progress wheel will appear on the Apple Watch. Plug the Apple Watch into a charger to prevent it from dying during the update process.
Once the update is installed, the Apple Watch will restart and run the latest software version.

Note: Once the installation starts, don’t restart, turn off, or disconnect the iPhone or Apple Watch unless Apple specifically instructs you to do so. The Watch may restart several times during the update. That’s normal, so don’t panic if the screen goes dark or the Apple logo appears.

What if watchOS 27 doesn’t appear?

If you don’t see watchOS 27 under Software Update, don’t immediately assume something is wrong.

I would check these things first:

Check your Apple Watch model. The supported list starts with Series 9, Ultra 2, and SE 3.
Your iPhone must be an iPhone 11 or newer, or an iPhone SE (2nd gen or newer), and it needs to run iOS 27.
Update your iPhone to iOS 27 first before trying to install watchOS 27.
Put the Apple Watch on its charger even if the battery is already high enough.
Give the update some time. Major watchOS updates can take a while to download, prepare, and install. A progress bar that appears stuck for a while doesn’t necessarily mean the update has failed.

All set with watchOS 27

Updating to watchOS 27 is a simple way to bring new features, smarter tools, and useful improvements to your Apple Watch. Once you confirm that your Watch and iPhone are compatible, the installation only takes a few steps.

With features like Workout Buddy, smarter Siri, the redesigned app grid, improved Smart Stack, new health features, and Liquid Glass refinements, there is plenty to explore after the update.

So, is your Apple Watch ready for watchOS 27, or are you still wondering which new feature you should try first?