A check box control in VB.NET is a graphical user interface element that allows the user to select or deselect an option. It is typically represented by a small square box that can be checked or unchecked by clicking on it. Check box controls are commonly used in forms and dialog boxes to allow users to make binary choices, such as selecting or deselecting a feature or agreeing to terms and conditions. In VB.NET, check box controls can be easily added to a form using the CheckBox class from the Windows Forms namespace.