NOTE: This article covers only the Mac side of printing contacts. It is known throughout the land that printing is looked upon as a dark art, and lo there are various and sundry paths one can take to achieve it. However, the half of the equation where the printer doesn't work right or won't line up the envelope or isn't recognized anymore is all troubleshooting for another day. That being said, let's continue by launching Contacts and choosing the one you need:
Choose a contact to print on the envelope
First, launch the Contact app. Hopefully it's all up to date and nice looking since you sync your contacts to iCloud so your iPhone always has the latest info. Find the contact you want to print out, and then press Command-P to get the Print dialog. In the regular sheet that drops down, you will see a preview of what will get printed. Generally this is an envelope, so if you want some mailing labels this will need some adjustment.
Show Details to dig into the magic of printing envelopes.
Click on the Show Details button in the lower left of the window, next to the “PDF” button. Then the sheet will expand out and give you loads more options for configuring how to print things out. From here you can go to the menu next to “Style” and choose from Mailing Labels, Envelopes, Lists, or a Pocket Address Book.
Then you can determine the adjustments for where you want the text to appear on your envelope, and if your return address should be on it, the font to use, etc. After you've set it up how you want it, hit the Print button and you're on your way.
This is where the magic happens.
Should you desire mailing labels instead, just choose that option from the drop down and feed the printer labels instead of envelopes. As we've previously mentioned, it can be handy to have a paper copy of your contacts, but getting to whip out an envelope on demand is another handy trick to have up your sleeve.