There has been extensive research on deep eutectic solvents (DESs), particularly those composed of choline chloride (ChCl) and acrylic acid (AA), due to the need for solvents that are both sustainable and customizable. This study investigates how the addition of structural isomers of butanol—1-butanol, 2-butanol, and 3-butanol—affects the density and volumetric behavior of a ChCl: AA (1:2) DES at temperatures between 293.15 and 323.15 K and atmospheric pressure. We performed experimental density measurements to find excess molar volumes (Vm^E), which were all negative. This means that the DES and alcohol molecules were very strongly associated with one other. As the butanol isomers became more branched, their interaction strength and packing efficiency went down. Thermodynamic simulation employing the Prigogine–Flory–Patterson (PFP) theory and the Extended Real Associated Solution (ERAS) model elucidated particular interactions, free volume effects, and departures from ideal performance. In the systems examined, ChCl–AA + 3-butanol demonstrated the most significant negative Vm^E, indicating a greater degree of structural disruption resulting from the inclusion of tertiary alcohol. This work demonstrates that the properties of DESs can be modified by adding alcohol, enabling the development of green solvents with tailored properties for advanced chemical processing applications.