High oxygen content titanium (HOC-Ti) was manufactured in-situ via wire arc additive manufacturing (WAAM), and its compositional segregation, microstructure and mechanical properties were studied. The results show that the microstructure of the HOC-Ti component is mainly manifested as acicular α colonies. As oxygen content increases, the acicular α of the sample is broadened and the colonies become larger. Due to the strengthening of oxygen and the grain size effect, the strength change trend is from high to low, and the elongation is reduced significantly. The fracture mechanism is changed from ductile rupture to cleavage fracture. When the oxygen content is 0.37 wt.%, its elongation is about 7%, and the ultimate tensile strength is more than 730 MPa, which is around double that of commercially pure titanium (CP-Ti).