Objectives: We aimed to explore the impact of time to percutaneous coronary intervention (PCI) (T2P) on 1-year mortality in non-ST-elevation myocardial infarction (NSTEMI) patients. Background: The current guidelines recommend an early invasive strategy for NSTEMI patients. However, impact of an early invasive strategy on mortality is a matter of debate. For that reason, real world data are of great value to determine the optimal treatment window. Methods: This retrospective single center cohort study was performed in a high-volume PCI center in Amsterdam, The Netherlands. Intermediate- and high-risk NSTEMI patients undergoing PCI were included. The main discriminant was timing of PCI after admission (T2P), stratified according to different time windows (7 days). We analyzed 1-year mortality and the time distribution of overall survival. Results: In total, 848 patients treated between January 1, 2016 and January 1, 2018 were included in the analysis. T2P was 7 days in 236 patients. The mean GRACE-risk score was 127.1 (SD 28.7), 130.0 (33.1), 133.8 (32.1), and 148.7 (34.6) respectively, p = 7 days (OR = 3.20; 95% CI = 1.06–9.68). Conclusions: In an unselected cohort of patients with NSTEMI, treatment by PCI 7 days after admission resulted in worse outcome.