As chemotherapy suffers from the limitation of non-selectivity towards cancer cells, resulting in severe side effects, the targeted delivery of anticancer drugs such as cisplatin using nontoxic nanomaterials has been under extensive examination. In such an approach, qualities such as biocompatibility, biodegradability, ease of synthesis (including the surface modifying possibility with targeting ligands), and the tunable encapsulation of chemotherapeutics make liposomes superior to other nanomaterials as drug nanocarriers. Despite ten liposome-drug formulations being approved for the market, none of them concern platinum-based anticancer drugs. This can be due to the problematic multistep synthesis of such systems and the use of ineffective analytical tools for their characterization. Consequently, the current study aims to propose a straightforward protocol for liposome–cisplatin system synthesis as well as a comprehensive method for their characterization based on the combination of capillary electrophoresis (CE) and inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS). Although the application of CE-ICP-MS has been reported in previous studies on liposome–cisplatin systems, the advantages of the optimized method proposed in our study include not only the possibility of the direct quantitative monitoring of liposome–metallodrug systems (all analytes of interest) but also their interactions with proteins in close-to-physiological conditions of analysis due to the applied tandem mass mode of the spectrometer. The present approach thereby facilitates overcoming the limitations of the strategies previously described in the literature, especially in the case of sulfur monitoring.