How do you add a label (title text) to a Checkbox in Flutter?

If you need a Checkbox with a label then you can use a CheckboxListTile.

  CheckboxListTile(
    title: Text("title text"), //    <-- label
    value: checkedValue,
    onChanged: (newValue) { ... },
  )

If you want the checkbox on the left of the text then you can set the controlAffinity parameter.

  CheckboxListTile(
    title: Text("title text"),
    value: checkedValue,
    onChanged: (newValue) { ... },
    controlAffinity: ListTileControlAffinity.leading,  //  <-- leading Checkbox
  )

Notes

• Since it is a ListTile, clicking anywhere on the row activates the onChanged() callback. You need to rebuild it with the correct checked values yourself, though. See this answer.
• An alternate solution would be to make your own widget using a Row with a Checkbox and a Text widget. You would probably want to wrap it in a gesture detector, though, so that taps on the text would also trigger an onChanged() callback. You could start with the CheckboxListTile source code as a reference.