Abstract Inflammatory processes are involved not only in coronary artery disease but also in heart failure (HF). Cardiogenic shock (CS) and septic shock are classically distinct although intricate relationships are frequent in daily practice. The impact of admission inflammation in patients with CS is largely unknown. FRENSHOCK is a prospective registry including 772 CS patients from 49 centers. One-month and one-year mortalities were analyzed according to the level of C-reactive protein (CRP) at admission, adjusted on independent predictive factors. Within 406 patients included, 72.7% were male, and the mean age was 67.4 y ± 14.7. Four groups were defined, depending on the quartiles of CRP at admission. Q1 with a CRP < 8 mg/L, Q2: CRP was 8–28 mg/L, Q3: CRP was > 28–69 mg/L, and Q4: CRP was > 69 mg/L. The four groups did not differ regarding main baseline characteristics. However, group Q4 received more often antibiotics in 47.5%, norepinephrine in 66.3%, and needed more frequently respiratory support and renal replacement therapy. Whether at 1 month (P trend = 0.01) or 1 year (P trend < 0.01), a strong significant trend towards increased all-cause mortality was observed across CRP quartiles. Specifically, compared to the Q1 group, Q4 patients demonstrated a 2.2-fold higher mortality rate at 1-month (95% CI 1.23–3.97, p < 0.01), which persisted at 1-year, with a 2.14-fold increase in events (95% CI 1.43–3.22, p < 0.01). Admission CRP level is a strong independent predictor of mortality at 1 month and 1-year in CS. Specific approaches need to be developed to identify accurately patients in whom inflammatory processes are excessive and harmful, paving the way for innovative approaches in patients admitted for CS. NCT02703038.