X‐ray‐diffraction studies carried out on Tb0.27Dy0.73Fe2−xCox(x=0,0.5,1.2,2.0) revealed that all compositions investigated retained the C‐15 cubic Laves phase structure. Magnetization and electrical resistivity measurements were carried out in the temperature range 77–800 K. Anomalies observed in the resistivity measurements have been identified corresponding to spin reorientation transitions occurring in this system. Some of these transitions have also been observed in the magnetization data. Magnetostriction and magnetomechanical coupling coefficient were measured on samples ofx=0, 0.5, and 1.2 prepared by arc melting as well as arc melting followed by zoning using an induction furnace. Magnetostriction and coupling coefficient were found to decrease with increase in cobalt concentration. Magnetostriction data on zoned samples revealed a change in the easy direction of magnetization from [111] to [100] in the case ofx=0.5.