This cross-sectional study addressed the relationship between coffee consumption and periodontitis in patients during the maintenance phase of periodontal treatment. A total of 414 periodontitis patients in the maintenance phase of periodontal treatment completed a questionnaire including items related to coffee intake and underwent periodontal examination. Logistic regression analysis showed that presence of moderate/severe periodontitis was correlated with presence of hypertension (Odds Ratio (OR) = 1.99, p < 0.05), smoking (former, OR = 5.63, p < 0.01; current, OR = 6.81, p = 0.076), number of teeth present (OR = 0.89, p < 0.001), plaque control record ≥20% (OR = 1.88, p < 0.05), and duration of maintenance phase (OR = 1.07, p < 0.01). On the other hand, presence of severe periodontitis was correlated with smoking (former, OR = 1.35, p = 0.501; current, OR = 3.98, p < 0.05), coffee consumption (≥1 cup/day, OR = 0.55, p < 0.05), number of teeth present (OR = 0.95, p < 0.05), and bleeding on probing ≥ 20% (OR = 3.67, p < 0.001). There appears to be an inverse association between coffee consumption (≥1 cup/day) and prevalence of severe periodontitis in the maintenance phase of periodontal treatment.