Recently, the development of green corrosion inhibitors and green inhibition strategies has become highly demanded due to the increased demand for green chemistry in the area of science and technology. This present research is about Dendrobium crumenatum (D. crumenatum), also known as pigeon orchid; a green additive to protect the mild steel coupon from corrosive effect in different seawater velocities. This study was held within 35 days of immersion with data interval of 7 days. Secondary metabolites in D. crumenatum play an important role in D. crumenatum as green additives. The chemical constituents of the D. crumenatum were investigated through Fourier-transform infrared spectroscopy (FTIR). The corrosion inhibition efficiency of D. crumenatum was analyzed through electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and Optical Microscope. To investigate the seawater velocity as disturbance factor to the corrosion inhibition, different seawater velocities ranging from 0 m/s, 0.074 m/s, 0.094 m/s, 0.114 m/s respectively were utilized using aerator. The rate of corrosion was tested via weight loss and potentiodynamic polarization. The present work showed that D. crumenatum has a good performance as green additive in minimizing corrosion effect on mild steel via the morphological analysis. Meanwhile, based on the result, highest velocities at 0.114 m/s had caused highest corrosion rate 0.19 mm/year after Day 35 which indicate that the oxidation process vigorously occurred at high velocity.