Background <p>Thyroid dysfunction and <i>Helicobacter pylori</i> (H. pylori) infection are both highly prevalent in Pakistan. Several studies have proposed a potential immunological link between H. pylori infection and autoimmune thyroid disease, though evidence remains controversial. Given the cross-sectional design of this study, causal relationships cannot be inferred; the objective was to determine whether a statistically significant association exists between H. pylori infection and thyroid dysfunction in adults attending a tertiary care hospital in Karachi, Pakistan.</p> Methods <p>A cross-sectional study was conducted over four months at Civil Hospital Karachi. Adult patients presenting with gastrointestinal symptoms were enrolled using consecutive sampling. H. pylori infection was confirmed using an immunochromatographic stool antigen test. Thyroid dysfunction was assessed by measuring thyroid-stimulating hormone (TSH) levels using the Electrochemiluminescence Immunoassay (ECLIA) technique, with normal TSH defined as 0.4–4.0 mIU/L; values outside this range indicated thyroid dysfunction. Statistical analysis was performed using SPSS version 23.0, applying chi-square tests and binary logistic regression. Odds ratios (ORs) with 95% confidence intervals (CIs) were reported; significance was set at <i>p</i> &lt; 0.05. Sample size was calculated based on an estimated H. pylori prevalence of 50% with a 95% confidence level and ± 6% margin of error, yielding 267 participants.</p> Results <p>A total of 267 participants were included. Thyroid dysfunction was identified in 19.3% of participants based on abnormal TSH levels. Although thyroid dysfunction was observed at a numerically higher frequency among H. pylori-negative participants, this difference was not statistically significant (OR = 1.376, 95% CI: 0.747–2.537, <i>p</i> = 0.305). H. pylori infection was more prevalent in male participants. Constipation was prevelant in hpylori positive patients but neither constipation nor diarrhea showed a statistically significant association with H. pylori infection.</p> Conclusions <p>In this cross-sectional study, no statistically significant association was observed between H. pylori infection and thyroid dysfunction. These preliminary findings do not support a significant association between the two conditions in this population; however, given the study’s methodological limitations, they are insufficient to make a definitive recommendation regarding routine thyroid screening in H. pylori-infected patients. Larger prospective studies incorporating thyroid autoantibodies, fT3/fT4 levels, and H. pylori strain typing are needed before any firm clinical conclusions can be drawn.</p> Clinical trial number <p>Not applicable.</p>