This tutorial aims to show how to make a C# Form with rounded corners, using a very simple method. It’s not actually our policy as we won’t use code here…

1. Select a background image for the Form(window) - it must have the Form’s size (if the Form is 300x200, the image must be 300x200 too).

In the tutorial, I’ll use something like this:

background image

2. Use a ‘specific’ color to cover the corners of the image - so it appears with rounded corners - it can be easily done by drawing a rectangle over the original image. This color will be set as transparent, so it will not show up with the window. For this it’s usually used the Magenta (R: 255, G: 0, B: 255) color. I recommend using it for the first time.

You’ll get something like this:

background rounded corners

3. Open Visual Studio or any IDE and create a Form Project.
On the right side, in the Properties Window look for BackgroundImage. option. Click Import and choose the image you made before.
Also in the properties, set the TransparencyKey to Magenta - so it won’t show the pink border around the Form.

4. Finally, set FormBorderStyle to none in order to hide the original borders/title bar and you’re done.

Now when you’ll open the window it will show the background image with nice, rounded corners:


You’ve probably noticed that the form isn’t moving - that’s because it has no title bar and border. No need to worry about that, you can find here a solution.