 <p>Validation doesn't work with knockout bindings....</p> <p>You have to duplicate the validation in client side. The faster way is using knockout validation plugin, but it is slow when you have a lot of data..</p> <p><a href="https://github.com/ericmbarnard/Knockout-Validation" rel="nofollow">https://github.com/ericmbarnard/Knockout-Validation</a></p> <p>Or you can just use jquery validation.</p>