Adding a Emoji to a Microsoft teams channel is super easy to do and helps highlight that channel’s purpose, making it stand out from the rest.

Let’s demo how to do this

First, Lets get an emoji into the copy / paste buffer. 

I use https://emojipedia.org to find my emoji and then click copy to have it ready to go. 
Second, Create or edit a channel name.  

If you're adding a new channel, click the ellipses (...) next to your team name that you'd like to add the channel to and click 'Add channel' from the menu.

If you're editing an existing channel, click the ellipses next to that channel name and from the pop up menu, click 'Edit this channel'.
Note - The General channel doesn't allow for its name to be edited.
Third, paste the emoji into the channel name and save the channel (in this case, since it's a new channel, click add).

That’s it, now you have a channel name with an emoji. Enjoy!