How to hide soft input keyboard on flutter after clicking outside TextField/anywhere on screen?

You are doing it in the wrong way, just try this simple method to hide the soft keyboard. you just need to wrap your whole screen in the GestureDetector method and onTap method write this code.

        FocusScope.of(context).requestFocus(new FocusNode());

Here is the complete example:

new Scaffold(

body: new GestureDetector(
  onTap: () {
   
    FocusScope.of(context).requestFocus(new FocusNode());
  },
child: new Container(
   //rest of your code write here
    )
 )

Updated

Starting May 2019, FocusNode now has unfocus method:

Cancels any outstanding requests for focus.

This method is safe to call regardless of whether this node has ever requested focus.

Use unfocus if you have declared a FocusNode for your text fields:

final focusNode = FocusNode();

// ...

focusNode.unfocus();

My original answer suggested detach method - use it only if you need to get rid of your FocusNode completely. If you plan to keep it around - use unfocus instead.

If you have not declared a FocusNode specifically - use unfocus for the FocusScope of your current context:

FocusScope.of(context).unfocus();

---

See revision history for the original answer.

Wrap whole screen in GestureDetector as

new Scaffold(

  body: new GestureDetector(
      onTap: () {
        // call this method here to hide soft keyboard
        FocusScope.of(context).requestFocus(new FocusNode());
      },
    child: new Container(
       -
       -
       -
        )
   )