How to create hyper link in ExtJS 4?

You can also use the html property of a label component and call a controller function from there. Example:

{xtype: 'label',
html: 'bla bla? <a href="#" onClick="javascript:appName.app.getController(\'myController\').showRegistration();">Register</a>'
}

I'd use an autoEl for this.

{
    xtype: 'component',
    autoEl: {
        tag: 'a',
        href: 'http://www.example.com/',
        html: 'Example.com'
    }
}

Here's a Fiddle