Apple Watch 4 iMessage microphone is grayed out.

Good afternoon McLendon296,

Welcome to the Apple Support Communities!

I understand the microphone is not working on your Apple Watch Series 4. Is the microphone greyed out for the Apple Messages app, or for all apps on the device?

Check to see if there are any restrictions for Siri & Dictation on your iPhone.

Use parental controls on your child's iPhone, iPad and iPod touch

Settings > Siri & Search

Settings > General > Keyboard

1. Disable Siri, and turn off your iPhone. Turn off your Apple Watch.
2. Turn on your iPhone first and enable Siri and dictation in the Settings app above.
3. Make sure Siri is working on your iPhone.
4. Then turn on your Apple Watch.

Restart your iPhone

How to restart your Apple Watch

Use Siri on your Apple Watch

Please reply to this thread if the issue persists after trying the steps above, and I'll do my best to help you with this!

Take care.

I just tried this process w/my Apple Watch 5, & it didn't work. Sometime ago, the iMessage microphone worked, but after the last or previous software update, it's been grayed out.

Thx for this suggestion, but doing the prescribed procedure via the watch didn't work, as I already had Dictation turned on.