Background: Thyroid dysfunction is common in critically ill neonates and has been repeatedly implicated in gastrointestinal dysmotility and sub optimal growth. Yet, the magnitude and nature of its relationship with feeding difficulties in the neonatal intensive care unit (NICU) remain uncertain. Objectives: We synthesized contemporary evidence on the prevalence of thyroid disorders among NICU patients, quantified the frequency of concomitant feeding difficulties, and explored mechanistic links and therapeutic implications. Methods: A systematic search of PubMed, Web of Science, Scopus and ScienceDirect was performed from inception to 1 March 2025. Very low birth weight and term neonates admitted to NICU settings were eligible. Two reviewers independently screened records, extracted data and assessed risk of bias with the Joanna Briggs Institute tool. Results: From 812 unique records, 10 studies met inclusion criteria (4 cohort, 3 case control, 1 prospective crossover trial, 2 case reports; cumulative N = 2 387 neonates). Congenital or acquired hypothyroidism predominated; one series reported delayed thyrotropin elevation and another synthesized thyroid dysfunction secondary to maternal Graves’ disease. Across studies, hypothyroid infants required significantly longer periods nil per os, tolerated lower enteral volumes and had more frequent gastric residuals than euthyroid peers. Initiation of L thyroxine—typically 5 15 µg kg⁻¹ day⁻¹—consistently accelerated achievement of full feeds and resolved abdominal distension. Quality appraisal rated eight studies moderate and two high. Conclusion: The best available evidence indicates that untreated thyroid hypofunction is an under recognized, reversible contributor to feeding intolerance in the NICU. Routine thyroid re evaluation in hard to feed infants and prompt thyroxine replacement when indicated may shorten parenteral nutrition dependency and hospital stay. Robust multicenter trials are warranted to define optimal screening intervals and dosing strategies.