Novel silicon-gallium-doped zinc oxide (SGZO) coated muscovite mica substrates are proposed for flexible light-emitting electrochemical cells (LECs). Inorganic muscovite mica substrates show advantages of good thermal stability, mechanical durability, and resistance to oxygen and moisture, which are promising substrates for flexible light-emitting devices. The SGZO film exhibits high transmittance and low sheet resistance through annealing treatment. Furthermore, the sheet resistance of SGZO film on mica substrate only increases by 20% after 104 bending cycles with a curvature radius of 10 mm. Blue, orange, red, and white LECs based on ion transition metal complexes are tested on the proposed substrates and the device performance of the LECs on mica/SGZO is comparable with that of the LECs on reference glass/SGZO. Less than 20% reduction in device efficiency of the mica/SGZO-based LECs are measured after 104 bending cycles. These results confirm that the SGZO coated mica substrates are good potential candidates for applications in flexible light-emitting devices.