Electrolytes are an important component in determining the performance and cycle life of ultracapacitors. Good electrolytes should have high conductivity, large electrochemical windows, excellent thermal and chemical stability, and negligible electrolyte depletion. Ionic liquids are ideal electrolytes to satisfy these requirements. In the present work, we developed easy-to-use methods to incorporate ionic liquids into a polymer matrix to synthesize gel polymer electrolytes. The obtained solid-state ionic liquid- incorporated gel polymer electrolytes (ILGPEs) are mechanically strong, electrochemically and thermally stable, and highly conductive. We have used these electrolytes to fabricate solid-state ultracapacitors. Large cell voltage, high performance, and long cycle life have been realized for these ultracapacitors.