How to remove padding around buttons in Android?

That's not padding, it's the shadow around the button in its background drawable. Create your own background and it will disappear.

My solution was set to 0 the insetTop and insetBottom properties.

<android.support.design.button.MaterialButton
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:insetTop="0dp"
        android:insetBottom="0dp"
        android:text="@string/view_video"
        android:textColor="@color/white"/>

For me the problem turned out to be minHeight and minWidth on some of the Android themes.

On the Button element, add:

<Button android:minHeight="0dp" android:minWidth="0dp" ...

Or in your button's style:

<item name="android:minHeight">0dp</item>
<item name="android:minWidth">0dp</item>

for MaterialButton, add below properties, it will work perfectly

<android.support.design.button.MaterialButton
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:insetTop="0dp"
    android:insetBottom="0dp"/>