Methylene blue is a widely used dye that can have severe negative impacts on the environment and human health. Adsorption is an effective method for removing it from wastewater, but the high cost of traditional adsorbents has motivated the research into low-cost alternatives derived from waste biomass. Designing a dye-removal process requires the knowledge of breakthrough curves. This paper assesses the use of banana peel as an adsorbent in a continuous process for the removal of methylene blue. The adsorption efficiency of lab-scale continuous systems using a stock solution of 0.5 g L−1 methylene blue was analyzed. The best performance was found at pH 6, with a particle size of 0.08–0.3 mm and a fixed bed height of 7.5 cm. The total adsorption capacity was 22.11 mg/g based on experimental data and 25.40 mg/g based on mathematical modeling (Thomas model). The saturation time was 53 h. According to the results, the process conditions and adsorbent characteristics have a critical role in the design of continuous adsorption systems. However, further research is needed to generalize conclusions about the process and include additional experimental data under different operating conditions.