Background: Renal transplant recipients are at a 100-fold increased risk of developing renal cell carcinoma (RCC), with a higher incidence of RCC in native kidneys than in allografts. Given that kidney transplant recipients typically possess only one functional kidney, it is critical for clinicians to heightened disease awareness. This systematic scoping review aims to provide an updated overview of the clinical characteristics, treatment, and outcomes of RCC in the allograft kidneys. Methods: We comprehensively searched the databases of MEDLINE and EMBASE until January 2024. Included studies were case reports, case series and retrospective analyses reporting RCC in the allograft kidney of renal transplant recipients. The review delineates the clinical presentation, time between kidney transplant and diagnosis, donor characteristic, mass size, histopathology and treatment outcome of RCC in the allograft kidneys. Results: Forty-two case reports and case series, along with eleven retrospective cohorts were found. 65 patients were identified in the case reports and case series, while 209 patients were reported in the retrospective study reviews. The review emphasizes that 75.4% of patients with allograft RCC were asymptomatic at the time of diagnosis, with the majority diagnosed through imaging surveillance. Symptomatic patients most commonly presented with gross or microscopic hematuria, elevated creatinine, abdominal or graft pain, respectively. 61.9% of recipients received their allograft from deceased donors, and 38.1% from living donors. The average time interval between kidney transplantation and the diagnosis of RCC spans 11.6 years, ranging from 6 months to 30 years. Papillary RCC and clear cell RCC (ccRCC) were the two most common histopathological diagnoses, with papillary RCC accounting for 53.3% and ccRCC for 34.2% of cases. A potential limitation is the inconsistent of long-term follow-up data for most of the subjects, which makes the outcome of this population uncertain. Conclusions: This systematic scoping review identified an average time interval of 11.6 years between kidney transplantation and RCC diagnosis, with a range from 6 months to 30 years. The majority of kidney transplant recipients with allograft RCC (75.4%) were asymptomatic, while the remainder presented with symptoms such as hematuria, elevated creatinine, abdominal or graft pain, weight loss, fever, malaise, or hypertension. The incidence of asymptomatic allograft RCC among kidney transplant recipients underscores the importance of vigilant post-transplant screening. Future research should investigate clinical outcomes and the cost-effectiveness of the screening practices in allograft kidney to develop preventive strategies.