Relaxation oscillation suppression in a short-cavity single-frequency distributed Bragg reflector (DBR) Er3+/Yb3+-codoped fiber laser is demonstrated. A tailored optoelectronic feedback circuit acting on the pump driver is designed to reduce the noise peak at the relaxation oscillation frequency of 1.15 MHz by 26 dB, to a relative intensity noise (RIN) value of -121 dB/Hz and thus the RIN value is below -120 dB/Hz across the whole frequency range. The noise suppression loop is integrated into the laser diode driver module and no laser beam quality degradation is observed.