The present invention relates to a novel expandable screen display device, which is an add-on device adapted to encase a wearable communication device such as a smart phone or a smart watch. The expandable screen display device comprises a first enclosure with a first control module, a second enclosure with a second control module, such that the first control module and the second control module are in wireless communication for selective expansion of the expandable screen display device according to user input received via a mobile software application residing on the wearable communication device.