[en] Two nonstoichiometric UAu_1–xSb₂ (x = 0.25, 0.1) single crystals are successfully synthesized using a flux method, and their physical properties are comprehensively studied by measuring the dc-magnetization and electrical resistivity. Evidence for at least three magnetic phases is found in these samples. In zero field, both samples undergo an antiferromagnetic transition at a relatively high temperature, and with further cooling they pass through another antiferromagnetic phase, before reaching a ferromagnetic ground state. Furthermore, the magnetic order can be tuned by varying the site occupation of Au. Such a tunable magnetic order may provide an opportunity for exploring the potential quantum critical behavior in this system. (paper)