Background: Cardiovascular and cerebrovascular diseases are major contributors to global morbidity and mortality. Increasing evidence suggests that systemic inflammation plays a critical role in the development, progression, and prognosis of vascular events. Hematological inflammatory markers such as neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune-inflammation index (SII) have emerged as potential predictors of adverse cardiovascular and cerebrovascular outcomes. Objectives: To evaluate the role of systemic inflammatory markers in predicting both cardiac and cerebrovascular events and to assess their association with disease severity and in-hospital outcomes among patients admitted to a tertiary care hospital in Gujarat. Methods: A hospital-based observational analytical study was conducted from March 2025 to November 2025 among 120 adult patients diagnosed with acute cardiac or cerebrovascular events. Consecutive sampling was used for participant recruitment. Demographic details, clinical characteristics, comorbidities, and laboratory parameters were recorded using a structured case record form. Inflammatory markers including NLR, PLR, SII, total leukocyte count, and C-reactive protein were assessed at admission. Statistical analysis was performed using SPSS version 26.0. Continuous variables were expressed as mean ± standard deviation, and categorical variables as frequencies and percentages. Chi-square test, independent t-test, and logistic regression analysis were applied. A p-value <0.05 was considered statistically significant. Results: Among the 120 study participants, 68 patients had cardiac events and 52 had cerebrovascular events. The mean age of participants was 59.6 ± 11.8 years, with male predominance. Hypertension was the most common comorbidity. Patients with cerebrovascular events demonstrated significantly higher mean values of NLR, PLR, SII, and CRP compared to cardiac event patients. Elevated inflammatory markers were significantly associated with severe vascular events and adverse in-hospital outcomes. Patients with unfavorable outcomes had markedly elevated mean NLR, PLR, and SII values along with longer hospital stay. Multivariate logistic regression analysis identified elevated NLR, PLR, and SII as independent predictors of adverse outcomes, with SII showing the strongest association. Conclusion: Systemic inflammatory markers, particularly NLR, PLR, and SII, are valuable predictors of severity and adverse outcomes in patients with cardiac and cerebrovascular events. These inexpensive and readily available biomarkers may serve as useful tools for early risk stratification and prognostication in routine clinical practice.