Spatiotemporal mode-locked fiber lasers are a type of ultrafast lasers for which the longitudinal and transverse modes of the multimode fiber cavities are locked via nonlinear interaction in the cavity. Here we report the experimental realization of a spatiotemporally mode-locked fiber laser with self-similar pulse evolution. The multimode fiber oscillator generates parabolic pulses at 1030 nm with 90 mW average power, a near-Gaussian beam quality (M-2 <= 1.4), and 2.3 ps (192 fs externally dechirped) pulse duration. Numerical simulations confirm the experimental observations of self-similar pulse propagation. These results will enable further investigation of nonlinear dynamics in spatiotemporal mode-locked fiber lasers. (c) 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement