Although clinical benefits of intravascular imaging-guided percutaneous coronary intervention (PCI) in patients with complex coronary artery lesions have been observed in previous trials, the cost-effectiveness of this strategy is uncertain. RENOVATE-COMPLEX-PCI (Randomized Controlled Trial of Intravascular Imaging Guidance vs Angiography-Guidance on Clinical Outcomes After Complex Percutaneous Coronary Intervention) was conducted in Korea between May 2018 and May 2021. This prespecified cost-effectiveness substudy was conducted using Markov model that simulated 3 states: (1) post-PCI, (2) spontaneous myocardial infarction, and (3) death. A simulated cohort was derived from the intention-to-treat population, and input parameters were extracted from either the trial data or previous publications. Cost-effectiveness was evaluated using time horizon of 3 years (within trial) and lifetime. The primary outcome was incremental cost-effectiveness ratio (ICER), an indicator of incremental cost on additional quality-adjusted life years (QALYs) gained, in intravascular imaging-guided PCI compared with angiography-guided PCI. The current analysis was performed using the Korean health care sector perspective with reporting the results in US dollar (1200 Korean Won, ₩=1 dollar, $). Willingness to pay threshold was $35 000 per QALY gained. A total of 1639 patients were included in the trial. During 3-year follow-up, medical costs ($8661 versus $7236; incremental cost, $1426) and QALY (2.34 versus 2.31; incremental QALY, 0.025) were both higher in intravascular imaging-guided PCI than angiography-guided PCI, resulting incremental cost-effectiveness ratio of $57 040 per QALY gained within trial data. Conversely, lifetime simulation showed total cumulative medical cost was reversed between the 2 groups ($40 455 versus $49 519; incremental cost, -$9063) with consistently higher QALY (8.24 versus 7.89; incremental QALY, 0.910) in intravascular imaging-guided PCI than angiography-guided PCI, resulting in a dominant incremental cost-effectiveness ratio. Consistently, 70% of probabilistic iterations showed cost-effectiveness of intravascular imaging-guided PCI in probabilistic sensitivity analysis. The current cost-effectiveness analysis suggests that imaging-guided PCI is more cost-effective than angiography-guided PCI by reducing medical cost and increasing quality-of-life in complex coronary artery lesions in long-term follow-up. URL: https://www.clinicaltrials.gov; Unique identifier: NCT03381872.