Cesium lead-halide perovskite nanocrystals are an emerging class of materials which potentially have different applications due to the several physical properties they exhibit. These properties are strongly dependent on the elemental composition of the nanocrystals and, to date, only few methods are available for their chemical analysis, such as scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDX). The present work aims at establishing a new, fast and simple method for the elemental analysis of cesium lead-halide perovskite nanocrystals exploiting total-reflection x-ray fluorescence (TXRF) spectroscopy. The method was validated using a synthetized set of samples and comparing the TXRF results with SEM-EDX data. The sample preparation consisted in suspending the perovskites in 2.0 ml of hexane and sampling 10 μl of the suspension for deposition on a preheated quartz carrier. The element recovery ranged between 82% and 118% for mixed-halide perovskites, while for single halide perovskites it improved to 86%–105%. The present method can be implemented and used also for the elemental characterization of other types of perovskite nanocrystals.