Transitions in care from hospital to primary care for older patients with chronic diseases (CD) are complex and lead to increased mortality and service use. In response to these challenges, transitional care (TC) interventions are being widely implemented. They encompass education on self-management, discharge planning, structured follow-up and coordination among the different healthcare professionals. We conducted a systematic review to determine the effectiveness of interventions targeting transitions from hospital to the primary care setting for chronically ill older patients. Randomized controlled trials were identified through Medline, CINHAL, PsycInfo, EMBASE (1995–2015). Two independent reviewers performed the study selection, data extraction and assessment of study quality (Cochrane “Risk of Bias”). Risk differences (RD) and number needed to treat (NNT) or mean differences (MD) were calculated using a random-effects model. From 10,234 references, 92 studies were included. Compared to usual care, significantly better outcomes were observed: a lower mortality at 3 (RD: −0.02 [−0.05, 0.00]; NNT: 50), 6, 12 and 18 months post-discharge, a lower rate of ED visits at 3 months (RD: −0.08 [−0.15, −0.01]; NNT: 13), a lower rate of readmissions at 3 (RD: −0.08 [−0.14, −0.03]; NNT: 7), 6, 12 and 18 months and a lower mean of readmission days at 3 (MD: −1.33; [−2.15, −0.52]), 6, 12 and 18 months. No significant differences were observed in quality of life. In conclusion, TC improves transitions for older patients and should be included in the reorganization of healthcare services.