Background: The unpleasant taste of polyethylene glycol (PEG) has been a hindrance to patients undergoing colonoscopy. Aim: This study aims to determine whether the addition of a vitamin drink (Mizone) to the 4L split-dose PEG regimen would be effective in improving the solution's palatability, and reducing patient discomfort during bowel preparation. Methods: The present prospective, single endoscopist-blinded, randomized controlled study randomly assigned patients into two groups: PEG + Mizone group (3.6 L of PEG solution plus 0.4 L of Mizone) and PEG group (4 L of PEG solution). Palatability was assessed using a Likert scale of 1–5. The adverse events, amount of unconsumed solution, and willingness to repeat the same process were recorded through a questionnaire. The present study was registered in the Chinese Clinical Trial Registry (ChiCTR2000034484). Results: A total of 132 patients were included. The demographic characteristics of these patients were comparable between the two groups. The palatability score (mean ± standard deviation [SD]) was higher in the PEG + Mizone group, when compared to the control group (4.00 ± 0.859 vs. 2.95 ± 0.999, p