Synthetic dyes such as indigo carmine pose a serious threat to the environment and human health due to their high stability and poor biodegradability. Adsorption is considered one of the superior methods for removing such pollutants owing to its high efficiency, low cost, and ease of application. In this study, a γ-Al2O3/carbon nanotube (CNT) complex was synthesized to investigate its adsorption performance toward indigo carmine dye removal from water, and was characterized using XRD, thermogravimetric analysis, N2 adsorption-desorption, and FESEM. The incorporation of CNTs decreased the specific surface area from 332.4 to 277.4 m2/g, while the average pore diameter increased from 2.7 to 3.2 nm and the specific pore volume remained nearly constant (0.22 cm3/g); this behavior was consistent with FESEM images showing entangled carbon nanotube networks partially occupying the pores of the alumina matrix around the alumina particles. Adsorption experiments were performed at 25 °C, pH 7, and an initial indigo carmine concentration of 100 μM. After 24 hours, a removal efficiency of 60.64% and an experimental equilibrium adsorption capacity of 56.28 mg/g were obtained. Kinetic analysis revealed that the pseudo-second-order model (R2 = 0.995) provided a better fit, with the calculated adsorption capacity (57.28 mg/g) showing good agreement with the experimental value. Comparison with spherical γ-alumina beads showed that the synthesized composite exhibited a higher experimental adsorption capacity (56.28 vs. 39.47 mg/g), attributed to the synergistic effect of γ-Al2O3 adsorption mechanisms combined with π-π interactions provided by the carbon nanotubes.