Background: The SABR-COMET randomized clinical trial found that stereotactic ablative radiotherapy (SABR) improved outcomes among cancer patients with oligometastatic disease. Yet, the cost of SABR along with the large number of patients with oligometastatic disease raises the important question of value. This study sought to evaluate the cost-effectiveness of SABR compared to standard therapy among cancer patients with oligometastatic disease. Methods: We constructed a Markov model to simulate treatment with stereotactic ablative radiotherapy or standard therapy among patients with oligometastatic cancers. The model derived transition probabilities from clinical trial data to estimate risks of toxicity, disease progression and survival. Healthcare costs and health utilities were estimated from the literature. Cost-effectiveness was estimated with an incremental cost-effectiveness ratio (ICER) defined as dollars per quality-adjusted life year (QALY), with an ICER less than $100,000/QALY considered cost-effective. One-way and probabilistic sensitivity analyses were used to examine model uncertainty. Results: The addition of SABR increased total costs by $54,279 and improved effectiveness by 1.20 QALYs compared with standard therapy, leading to an ICER of $45,162/QALY. The model was sensitive to assumptions about tumor progression, though the model was not sensitive to assumptions about survival or cost of treatment. The cost of SABR would need to increase approximately six-fold from $12,241 to $78,151 before SABR becomes cost-ineffective. Probabilistic sensitivity analyses demonstrated that SABR was the cost-effective treatment option 97.2% of the time. Conclusions: The addition of SABR increased costs and improved quality adjusted survival, overall leading to a cost-effective treatment strategy for patients with oligometastatic cancer.