We report self-starting mode-locking of a diode-pumped super-stretched unidirectional ring laser based on a 26 m cladding-pumped Yb3+-fiber and an internal grating dispersion compensation. The long fiber resulted in an extremely high pulse stretching ratio inside the cavity of about 500 which is more than one order of magnitude above previously demonstrated laser systems. This system was passively mode-locked by nonlinear polarization rotation and generated pulses with 40 nm bandwidth at 1095 nm, a pulse energy of about 9.5 nJ and an output power of 630 mW.