We report on an ytterbium-doped monolithic fiber laser at a wavelength of 1018 nm with an output power of 200Win continuous wave operation. The optimal parameters for setting up such a high-power fiber laser with an ytterbiumdoped fiber are investigated and discussed in detail. An in-house-developed pump light stripper and a single-mode fused fiber coupler were applied to use the fiber laser for core-pumping of ytterbium-doped high-power fiber amplifiers in a monolithic setup.