The implementation of a geriatric oncology service is challenging in both high-income and low-and-middle-income countries. The Octavio Frias de Oliveira Institute of Cancer of Sao Paulo (ICESP) is a tertiary healthcare complex of the Clinics Hospital of the University of Sao Paulo Medical School and is considered a model of excellence in oncology in Latin America. The objective of this manuscript is to describe 10 years of the geriatric oncology service at ICESP and the challenges for its implementation. We performed a narrative description of the ICESP’s geriatric oncology service and a general retrospective descriptive analysis of data collected from routine structured medical records of patients referred to the service from 2011 to 2021. This article highlights the different settings in which the service operates (outpatient, pre-operative and hospital follow-up). In this period, 1,700 patients were assessed for preoperative evaluation (median age 83.9, SD 4.95), 468 patients were evaluated for therapeutic decision (median age 79.4, SD 7.38), 968 in general geriatric oncology care outpatient clinics from 2012 to 2021 (median age 78.7, SD 7.91) and 1,391 inpatient evaluations. In the past 10 years, our geriatric oncology team has grown exponentially and changed its characteristics in order to adjust them to the hospital demands, raising awareness among the oncology teams about the benefit of using geriatric assessment and promoting multidisciplinary discussions.