The addition of Fe and Mn to Ti has previously been considered in binary Ti-Fe and Ti-Mn alloys. However, their combined addition has not been properly exploited. In this study, simultaneous lean additions of Fe and Mn were used to create new metastable Ti alloys to be processed via powder metallurgy. It was found that lean additions of Fe and Mn result in the sintered metastable Ti alloys having a lamellar structure. Such microstructure is composed of colonies with comparable size and finer α+β lamellae as the amount of Mn and Fe increases. Furthermore, Mn is a stronger β stabiliser than Fe, and leads to finer microstructures. The addition of the Fe and Mn powder particles lowers the compressibility but increases the densification due to high diffusivity of these elements. Consequently, the amount of residual porosity decreases (8.2 → 7.2%) for higher additions of Fe and Mn. Moreover, the sintered metastable Ti alloys become less ductile but stronger (YS: 608–702 MPa for YS and 678–739 MPa for UTS) as the amount of alloying elements increases. Dimples generated from residual pores and fracture at the colonies/α+β lamellae boundaries comprise the fracture surface of the sintered metastable Ti alloys. The alloys fail in an intergranularly ductile manner.