In this paper, a new type of single-mode embedded dye-doped electro-optic (EO) polymeric waveguide switch based on cross-linkable negative photoresist was successfully designed and fabricated using direct photodefinition technique. The optical properties of the UV cross-linkable poled polymer were characterized. By optimizing the poling temperature and the dopant levels of Disperse Red 1, the DR1/SU-8 material showed excellent photostability and exhibited an EO coefficient, γ33, of 25 pm/V. The characteristic parameters of both the waveguide and the electrode were carefully designed and simulated by MATLAB program. The Mach-Zehnder interferometer switch on-off time obtained was about 6 μs. The new fabrication technique is a simple, rapid, and controllable process. The easy-to-fabricate waveguide structure is suitable for planar active lightwave circuit applications. The dye-doped polymer photosensitive waveguide devices will be very useful in realizing EO modulators and switches.