We evaluated the 3-year clinical outcomes of early invasive (EI) and delayed invasive (DI) strategies in older and younger adults with non-ST-segment elevation myocardial infarction (NSTEMI) undergoing successful new-generation drug-eluting stent (DES) implantation to reflect current real-world practice. Overall, 4513 patients with NSTEMI were recruited from the Korea Acute Myocardial Infarction Registry-National Institute of Health and divided into two groups according to age: group A (age ≥ 65 years, n = 2253) and group B (age < 65 years, n = 2260). These two groups were further divided into two subgroups: group EI (A1 and B1) and DI (A2 and B2). The primary clinical outcome was the occurrence of major adverse cardiac and cerebrovascular events (MACCEs), defined as all-cause death, recurrent MI (re-MI), any repeat coronary revascularization, or stroke. The secondary clinical outcome was definite or probable stent thrombosis (ST). In both groups A and B, after multivariable-adjusted and propensity score-adjusted analyses, MACCE (group A, p = 0.137 and p = 0.255, respectively; group B, p = 0.171 and p = 0.135, respectively), all-cause death, cardiac death (CD), non-CD, re-MI, any repeat revascularization, stroke, and ST rates were similar between the EI and DI groups. When including only those with complex lesions, the primary and secondary clinical outcomes were not significantly different between the EI and DI groups. In the era of new-generation DESs, major clinical outcomes were not significantly different between the EI and DI strategies in both older and younger adults with NSTEMI.