Systems and methods for remote authentication using mobile single sign on credentials are disclosed. In some implementations, a proxy server receives, from a web access device, a request to access a secure online resource via the web access device. The proxy server receives, from a mobile device different from the web access device, one or more credentials for accessing the secure online resource. The proxy server determines that a geographic distance between the web access device and the mobile device is less than a geographic distance threshold. Upon determining that the geographic distance between the web access device and the mobile device is less than the geographic distance threshold, the proxy server enables the web access device access to the secure online resource.