Herein, a new example of relay catalysis, using a combination of Mn2(CO)10 and an iridium-based photocatalyst, is reported. In our relay catalytic reaction, the Mn catalyst and iridium-based photocatalyst catalyze the reaction at different stages in the desired sequence under the same reaction conditions, and do not inhibit each other. This convenient method transforms a broad scope of alkyl iodides into the corresponding gem-difluoroalkenes via C(sp3)-C(sp3) bond construction. The protocol has good functional group tolerance and is suitable for the late-stage modification of multifunctional complex molecules.