This work examined the effects of dissolved gas degree of saturation (DOS) on sonochemical reaction yields in both a one-dimensional (1D) microspace and a three-dimensional (3D) millimeter-sized space. The extent of each reaction was monitored by measuring sonochemiluminescence (SCL) intensity at 213 kHz. The results demonstrated that, at relatively low levels of power density, selecting a solution DOS in the supersaturation range at atmospheric pressure resulted in higher yields per unit volume in the 1D space compared to that obtained from the 3D space. This effect is attributed to a decrease in the cavitation threshold of the 1D reaction system since, at low power density, the 1D space represents a more homogeneous reaction volume. Comparing the highest SCL intensity levels obtained from the 3D and 1D reactions shows that enhancing the reaction yield in the 1D space requires higher DOS values than are required to generate elevated yields in the 3D space. The 3D space contains a greater concentration of bubbles than the 1D space, but many of these are ineffective at promoting the reaction. Thus, reactions in the 3D environment require not only the application of higher power density levels but also a lower DOS, so as to allow the bubbles to undergo the violent pulsations necessary to facilitate the sonochemical reaction.