We present a simple and convenient one step route to prepare a series of chalcospinels Fe1−xCuxCr2S4 employing high frequency sound waves. The magnetic and electronic transport properties of the as-prepared spinels were studied, and this simple, easy, and efficient synthetic route may further encourage wider application of Cu-doped Fe chalcogenides in solid state magnetoelectronic devices. Furthermore, the adopted synthetic route highlights a one-pot synthesis employing organometallic precursors such as metal carbonyls, ethylenedimine, and elemental sulfur. The ease of synthesizing such complex spinel structures of Fe1−xCuxCr2S4 chalcogenides with x=0.3, 0.4, and 0.6 has been highlighted in this work. The rapid cavitational collapse results in sulfur deficiency in the system, which drastically alters the conduction behavior. All the compositions studied show a negative magnetoresistance response except for x=0.3 which exhibit an unusual positive magnetoresistance effect. Such an effect has been attributed to the sulfur deficiency occurring during the rapid cavitational collapse. Our experimental results provide one effective method for synthesis of doped ternary chalcospinels exhibiting magnetoresistive properties.