Make sure you install the font.

To open the settings editor: from the Code menu, choose Preferences > Settings, or use keyboard shortcut Ctrl+, (Cmd+, on Mac).

To enable FiraCode in the settings editor: under "Commonly Used", expand the "Text Editor" settings and then click on "Font". In the "Font Family" input box type Fira Code, replacing any content. Tick the check box "Enables/Disables font ligatures" under "Font Ligatures" to enable the special ligatures.

Visual Studio Code allows you to also edit the underlying settings.json config file. First open the settings editor as described above, then click the "curly brackets" icon to open the settings.json file.

Then paste the following lines and save the file.

"editor.fontFamily": "Fira Code",
"editor.fontLigatures": true,

If this doesn't work for you, you can try:

1. restarting VS Code;
2. wrapping the "Fira Code" section with additional apostrophes:

   "editor.fontFamily": "'Fira Code'",
   "editor.fontLigatures": true,

To achieve different weights, add one of the following (verified on Mac/Windows 10):

    "editor.fontWeight": "300" // Light
    "editor.fontWeight": "400" // Regular
    "editor.fontWeight": "450" // Retina !! Only works with FiraCode-VF.ttf installed, see below when using separated font files (the normal case).
    "editor.fontWeight": "500" // Medium
    "editor.fontWeight": "600" // Bold

To use Retina weight when not using FiraCode-VF.ttf, change fontFamily to FiraCode-Retina if on macOS (exactly that, no spaces):

    "editor.fontFamily": "FiraCode-Retina",

...or to Fira Code Retina if on Windows or Linux:

    "editor.fontFamily": "Fira Code Retina",

Since version 1.40, you can define stylistic sets in settings.json:

"editor.fontLigatures": "'calt', 'ss01', 'ss02', 'ss03', 'ss04', 'ss05', 'ss06', 'zero', 'onum'"

To avoid possible bugs, you must uninstall Fira Code 1.x before installing Fira Code 2+.

• Disable ligatures in unwanted contexts (be aware of the issues)