Malignant pericardial effusion (MPE) is a life-threatening condition in patients with cancer, with common recurrences after simple pericardiocentesis. Consequently, the intrapericardial instillation of sclerosing or cytotoxic agents has been explored, with limited evidence from small studies with different methodologies. We undertook an observational, retrospective, single-centre study, including all patients diagnosed with a solid neoplasm and clinically significant and/or recurrent, cytology-confirmed MPE, treated with Intrapericardial Instillation of Cisplatin (IPIC), between 2009 and 2022. Patients with hematological malignancies were excluded. The procedure followed a multidisciplinary approach and a standardized protocol. Variables collected included baseline patient characteristics, neoplasm details, MPE impact, adverse events (AEs) from procedures (pericardiocentesis and IPIC) and outcomes (time to MPE recurrence and survival). This study adhered to the STROBE guidelines. A total of 41 patients were included, 51% female, with a median age of 61 (51–69) years. Non-small cell lung cancer (NSCLC) was the predominant primary tumour (78%) and in 44% of the cohort, MPE was identified at cancer diagnosis. Most patients (90.2%) presented symptoms related to MPE at diagnosis, and 88% had cardiac tamponade on echocardiography. IPIC was administered a median of four times. IPIC-related AEs occurred in 10 patients (24.4%), with transient atrial fibrillation (AF) being the most frequent one. Two patients (4.9%) experienced MPE recurrence within 30 days after IPIC. The median survival time from MPE diagnosis was 161 days (5.4 months; IQR 73–455 days). IPIC appears to be a feasible, effective and safe option for reducing the risk of MPE recurrence, mainly in NSCLC.