Background: Ibrutinib, an oral Bruton's tyrosine kinase inhibitor, is approved for the treatment of chronic lymphocytic leukemia (CLL) in both upfront and relapsed/refractory. The prevalence of CLL is very low in India compared to western countries. Hence, the real-world data regarding efficacy and safety of Ibrutinib among the Indian population is very scarce. In this study, we aim to examine the toxicity profile, treatment response, and survival outcomes among Indian patients with CLL treated with Ibrutinib. Methods: In this retrospective study, we recruited all consecutive patients diagnosed with CLL, both treatment naïve (TN) and relapsed/refractory (R/R) CLL, on Ibrutinib (daily dose of 420 mg), registered at the Department of Medical Oncology, All India Institute of Medical Sciences, New Delhi, India between April 2016 and December 2021. Diagnosis of CLL, an indication of treatment, and response assessment were based on the recent guidelines (2018) from the International Workshop on CLL (iwCLL). Results: A total of 90 patients were recruited in this study, of which 33 were newly diagnosed and 57 had R/R CLL. Median age of the cohort was 60 years (range, 35–80 years) and male to female ratio was 3:1. The median total leukocyte count was 55x10⁹/L and Del 17p was detected in 18% of cases. The R/R cases had received a median of 1(1-3) prior line of therapy. Overall response rate was observed in 76(84.4%), complete response was in 18 (20%) cases, partial response (PR) was in 49 (54.4%) cases, and in 9 (10%) cases PR with lymphocytosis (PR-L) was observed. With a median follow-up period of 15 months (4-60), 2-year progression-free survival (PFS) was 80% for the whole cohort. The median PFS was not reached in TN cases and was 18 months in R/R cases. Grade-3/4 adverse events (A/E) were seen in 17 (29.8%, n = 57) of R/R cases and in 3 (9.1%,n = 33) of TN cases. The most common Grade-3/4 A/E were infections in 19 (21.1%), (Varicella: 7, Pneumocystis: 6, Aspergilosis: 2, Mucormycosis: 1, Disseminated tuberculosis: 1, Encephalitis: 1, Others: 1) and cytopenias in 9 (10%) of cases. Other A/E were fatigue in 6 cases, arthralgia in 3, bleeding in 2, cutaneous rash in 2, reactivation of hepatitis-B in 2, diarrhea in 2, arrhythmia in 2, and autoimmune hemolytic anemia in one case. Ten patients (11.1%) had a dose reduction due to AE. The discontinuation rate was 27 (30%), due to progressive disease in 18 patients and due to adverse events in 9 patients. Twenty patients died, 14 due to disease progression or Richter's transformation, 5 due to infections, and 2 due to other reasons. Conclusions: This is the largest study of ibrutinib from India. Ibrutinib is safe and effective in upfront and R/R cases of CLL. Infections are the most common adverse event in R/R cases. Acyclovir and Co-trimoxazole prophylaxis can be considered in R/R cases of CLL in routine clinical practice . Arrhythmias were rare A/E as compared with the available literature.