In this research, the gold nanoparticles (GNPs) obtained by sono-electrochemical fabrication were prepared via the addition of a base solution, sodium hydroxide (NaOH), into the growth solution. The effect of the amount of NaOH on the growth of GNPs was investigated. The growth solution was improved to blend collocated acetone, cetyltrimethylammonium bromide (CTAB), and NaOH for the evenness control of GNPs. The excessive condensation reaction resulting from acetone was inhibited by adding 70 μl of NaOH to the growth solution to build a micelle template. Uniform and spherical GNPs with an average diameter of 25.5 nm and an absorption peak at 527 nm were obtained because the interaction between free electrons and hydroxyl groups loosened the micelle template. The cluster agglomeration and size distribution of GNPs were also improved according to transmission electron microscopy (TEM) observation. The results of this study can be applied to sensors to improve their sensitivity by adding more nanoparticles or enhancing the sensor signal.