The effectiveness of colonoscopy is directly affected by the quality of the patient’s bowel preparation. Patients with lower socioeconomic status (SES) are at increased risk of having suboptimal bowel prep quality. Patient navigators can play a key role in clarifying bowel prep instructions. The aim of the present study was to examine the quality of bowel prep and its predictors among individuals of low SES undergoing screening colonoscopy with patient navigation. Participants (N = 607) were individuals of low SES who completed a screening colonoscopy with patient navigation. Demographic information was collected after the participants received a primary care referral for a screening colonoscopy. After the colonoscopy was completed, medical charts were reviewed to document the colonoscopists’ bowel prep quality ratings. A total of 6.8% (41/607) of the sample had poor bowel prep, which significantly correlated with having a colonoscopy that did not reach the cecum. If fair preps were included, approximately 19.3% (117/607) of our cohort would be considered to have suboptimal bowel prep. Our suboptimal bowel prep rates were better than those reported from other low SES samples.