To make FontAwesome icons visible in Android Studio XML designer you can.
- Create custom view
- Apply font in constructor
- Add custom attr if you want to set font from xml
Here is full demo code in gist
Demo img with code from comment:

Important parts: (pretty much the same as Declaring a custom android UI element using XML but with small tuning)
TextViewWithFont.java - Custom view class
import android.content.Context;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import android.widget.TextView;
public class TextViewWithFont extends TextView {
public TextViewWithFont(Context context) {
super(context);
init(context, null, 0);
}
public TextViewWithFont(Context context, AttributeSet attrs) {
super(context, attrs);
init(context, attrs, 0);
}
public TextViewWithFont(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init(context, attrs, defStyle);
}
private void init(Context context, AttributeSet attrs, int defStyle) {
// Load attributes
TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.TextViewPlusFont, 0, 0);
try {
String fontInAssets = ta.getString(R.styleable.TextViewPlusFont_customFont);
setTypeface(Typefaces.get(context, "fonts/"+ fontInAssets));
} finally {
ta.recycle();
}
}
}
res/values/attrs.xml - Need this to use app:customFont="fontawesome-webfont.ttf"
in our layout xml.
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="TextViewPlusFont">
<attr name="customFont" format="string"/>
</declare-styleable>
</resources>
Typefaces.java - Helper class to reuse fonts (Cache for fonts)
import android.content.Context;
import android.graphics.Typeface;
import android.util.Log;
import java.util.Hashtable;
public class Typefaces {
private static final String TAG = "Typefaces";
private static final Hashtable<String, Typeface> cache = new Hashtable<String, Typeface>();
public static Typeface get(Context c, String assetPath) {
synchronized (cache) {
if (!cache.containsKey(assetPath)) {
try {
Typeface t = Typeface.createFromAsset(c.getAssets(),
assetPath);
cache.put(assetPath, t);
Log.e(TAG, "Loaded '" + assetPath);
} catch (Exception e) {
Log.e(TAG, "Could not get typeface '" + assetPath
+ "' because " + e.getMessage());
return null;
}
}
return cache.get(assetPath);
}
}
}
activity_main.xml - Layout and how to use TextViewWithFont custom view
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<com.example.TextViewWithFont
xmlns:app="http://schemas.android.com/apk/res/com.example"
app:customFont="fontawesome-webfont.ttf"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="\uf1e2"
android:textSize="60dp"/>
</LinearLayout>