Optical frequency combs (OFCs) have become essential tools in a wide range of metrological and scientific research fields. However, in the reported literature, OFCs that cover the visible spectral range have a limited bandwidth and pulse energy. These drawbacks limit their potential applications, such as high-signal-to-noise ratio spectroscopic measurements. In this work, we demonstrate a broadband, high-power optical frequency comb covering the visible to near-infrared range (550 nm to 900 nm) with a high average power of approximately 300 mW. This is accomplished by the power scaling of optical pulses from a fully stabilized Er:fiber comb, coherent spectral broadening and finally the utilization of a PPLN's χ(2) nonlinearity. The broadband, high-power, fully stabilized visible OFCs showcased in this work offer reliable laser sources for high-precision spectroscopic measurements, imaging, and comparisons of optical clocks.