Aims: Describe the clinical yield of FDG-PET CT imaging in early-stage oral cavity squamous cell carcinoma (OCSCC) and estimate the cost effectiveness of routine FDG-PET scans in this cohort using a health-economic model parameterised from cohort data and published literature. Methodology: Single-institution retrospective cohort of 199 patients at the Royal Melbourne Hospital from 2017-2023 with biopsy confirmed T1 and T2 OSCC. Clinicopathological data and management from medical records were extracted, Direct PET programme cost was calculated at the Medicare Benefits Schedule 85% rebate level (A$810.05 per scan). Cost offsets were modelled for avoided futile neck dissection in PET-detected distant metastasis, additional workup triggered by management change, and stage-migration savings from incidentally detected non-distant malignancies (thyroid, lung, other). QALY impact was modelled cost offsets and negative drivers including early-detection gains and overdiagnosis/false-positive losses. The incremental cost-effectiveness ratio (ICER) was compared against a willingness-to-pay threshold of A$50,000/QALY, with one-way deterministic sensitivity across plausible assumption ranges. Results: Of 199 patients, 87 underwent FDG PET. PET identified occult distant metastasis in 5 scanned patients, prompted management change in 41, and detected 37 non-distant incidental findings. Incidental imaging detected one early-stage lung adenocarcinoma curatively resected by VATS. Direct MBS-level PET programme cost was A$70,474 (A$810/scan). At base-case assumptions, net programme cost was −A$11,037 with +2.98 incremental QALYs (ICER dominant). Cost-effectiveness was retained across A$25,000–A$100,000/QALY thresholds. Conclusion: Routine staging FDG-PET in early-stage OSCC was modestly cost-incurring but is cost effective considering the downstream effects of health costs in QALY. This was driven principally by the early detection incidental clinically significant lung cancer as lung cancers are expensive to treat.