Turn on your computer and launch iTunes. Click the "Finder" icon in the dock of your Mac. Then, click "Applications" in the left pane of the "Finder" window. Double-click "iTunes" from your "Applications" folder.

Create a playlist in iTunes by clicking the "Plus" icon in the lower left-hand corner of iTunes. Name the playlist something memorable like "M3U."

Locate the M3U file that you want to convert. Drag the file into the playlist you created. To do this, simply click the file and use your mouse to drag it on top of the playlist in iTunes. Each individual song is loaded in iTunes.

Change the encoding option on iTunes to "MP3." To do this, click "iTunes" and then "Preferences." From this menu, click "Import Settings." Click the "Import Using" drop-down menu and select "MP3 Encoder." Click "OK" twice to save your settings.

Select all of the files in the playlist. Then press "Control" on your keyboard and click the mouse. This opens a list of options. Select "Create MP3 Version" from the options. All of the files from the M3U file are converted into MP3s.