A modular and scalable high-power fiber laser system is configurable to generate 1 kW or more of laser output, and includes one or more separable pump modules separately disposed from each other, each pump module including a plurality of fiber-coupled component pump sources optically combined by one or more fiber-based pump module pump combiners, each pump module providing one or more pump module fiber outputs, and a gain module separately disposed from the one or more separable pump modules and including one or more gain module pump fiber inputs optically coupled to corresponding ones of the pump module fiber outputs, and including a gain fiber optically coupled to the one or more gain module pump fiber inputs, the gain fiber configured to generate a gain module fiber output power scalable in relation to the number and power of said pump module fiber outputs coupled to the gain fiber.