Epitaxial growth of GaAs on Si commonly employs a high‐temperature (≳850 °C) oxide desorption step. In this letter, we report the first epitaxial growth of GaAs on Si without the need for this high‐temperature treatment. This method utilizes a final HF treatment whereby the Si surface dangling bonds are terminated by hydrogen with a resultant (1×1) bulk‐like surface structure. Upon medium temperature heat treatment (×500 °C), hydrogen leaves the surface leading to the common orthogonal 2×1 surface reconstruction. High quality GaAs epitaxial layers were successfully grown on these 2×1 reconstructed Si surfaces with the pregrowth substrate preparation temperatures of as low as 600 °C.