In this work, a facile one-pot method was used to synthesize the co-modified carbon nanotube adsorbent(CB/MMCNT) of cucurbit[7]uril and Fe3O4. A series of characterizations were utilized to confirm the successfulsynthesis of the adsorbent. VSM and separation experiments demonstrated that the adsorbentexhibited excellent magnetic separation performance and could achieve rapid separation within 30 s. BET results show that the adsorbent has excellent specific surface area (67.438 m2/g). Subsequently, threecationic dyes, namely Methylene blue (MB), Malachite green (MG), and Gentian violet (GV), were utilizedin batch adsorption experiments. A strong adsorption effect on cations is exerted by the adsorbentthrough hydrogen bonds, electrostatic interactions, p-p conjugation effects and hydrophobic interactions. Under the optimal conditions (pH = 6, T = 300 min, C0 = 1000 mg/L), the maximum adsorptioncapacity of CB/MMCNT to MB, MG, and GV was 851.5 mg/g, 720.2 mg/g, and 563.4 mg/g. The adsorptiondata could be well fitted by both the pseudo-second-order kinetic model (R2 > 0.99) and Langmuir isothermmodel (R2 > 0.99). Thermodynamic data indicated that the adsorption process was spontaneousand endothermic. Moreover, the cyclic reuse performance of CB/MMCNT was evaluated through 7 cyclesof recycling experiments, which demonstrated that it maintained a high dye removal rate (MB 84%, MG78%, GV 81%), indicating its excellent reusability. Additionally, CB/MMCNT still maintained its impressivecationic dye removal performance (MB 95.8%, MG 92.7%, GV 92.2%) when tested in practical water environments. Overall, CB/MMCNT is a promising, environmentally friendly, efficient, and sustainable adsorbentfor removing cationic dyes.