Background: Iron deficiency anemia (IDA) and thyroid dysfunction are common disorders worldwide, especially among women of reproductive age. Both conditions exert substantial effects on metabolic and physiological processes, potentially leading to fatigue, cognitive impairment, and various systemic complications. Emerging evidence suggests that the biochemical pathways of thyroid hormone synthesis and regulation may be influenced by iron status, given iron’s critical role as a cofactor for thyroid peroxidase. However, the extent and mechanisms of this interrelationship, as well as the clinical implications, remain incompletely understood. Methods: In this cross-sectional study, 200 adult participants (aged 18–65) were recruited from a tertiary care hospital between January and December 2024. All participants underwent complete blood count (CBC), serum ferritin measurement, and thyroid function tests (T3, T4, TSH). Those with chronic kidney disease, acute infection, or known genetic anemia were excluded. Data on demographic variables and potential confounders (nutritional status, comorbidities) were collected via standardized questionnaires. Statistical analyses included Pearson correlations, multiple linear regressions, and subgroup comparisons. Results: A significant negative correlation was observed between serum ferritin and TSH levels (r = −0.41, p < 0.01). Additionally, participants with IDA (n = 80) displayed lower mean total T4 levels compared to non-anemic individuals (8.2 ± 1.3 µg/dL vs. 9.1 ± 1.5 µg/dL, p < 0.05). Regression analyses suggested that iron status independently predicted about 12% of the variance in T4 levels after adjusting for age, sex, and body mass index. Subgroup comparisons showed that individuals with moderate-to-severe anemia were more likely to exhibit subclinical hypothyroidism. Conclusion: The findings support a meaningful interrelationship between IDA and thyroid hormone dysfunction. Routine screening for both conditions, particularly in high-risk groups, and integrated management strategies may improve patient outcomes.