We report a dual-wavelength-pumped all-fiber continuous-wave (CW) laser operating at 3.55 µm that reached an output power of 14.9 W, which is, to the best of our knowledge, a record. The laser cavity, made of an erbium-doped fluoride fiber and bounded by two fiber Bragg gratings (FBGs), operates at an overall optical efficiency of 17.2% and a slope efficiency of 51.3% with respect to the 1976 nm launched pump power. The all-fiber design of the cavity not only allows for significant power scaling of the laser output, but also improves its long-term stability at high output power. The cavity design was set according to a numerical optimization that showed very good agreement with the experimental results.