Herein, we describe a novel device configuration for a double-plate electrowetting-on-dielectric system with a floating top-electrode. As a conventional double-plate EWOD device requires a grounded electrode on the top-plate, it will cause additional fabrication complicity and cost during the encapsulation process. In this work, we found that by carefully designing the electrode arrangement and configuring the driving electronic circuit, the droplet driving force can be maintained with a floating electrode on the top-plate. This can provide the possibilities to integrate additional electrical or electrochemical sensing functions on the top-plate. We use both finite element analysis and the fabricated system to validate the theory, and the results indicate that floating top-electrode EWOD systems are highly reliable and reproducible once the design considerations are fully met.