How can I chat with friends while in a LoL match?

Solution 1:

You can type /w username message to message an online friend. If your friend replies to the initial message, you can just type /r message/. If you want to send another message without a response, you have to use the /w method again.

The /r method will automatically fill in the username of the friend you are having the conversation with when you start typing the message. (It fills it in with the last user that messaged you)

/w = whisper

/r = reply

They have to be on your friend list as well as in the same region as you for this to work.

If you have a friend that thinks it is fun to spam you during a match, you can use /mute username, which will stop chat for your game's duration. I would not recommend using /ignore username as it will remove your friend from your friend list.