This article analyses the structural preparedness for cyber diplomacy in the algorithmic age by examining whether the selected European Union member states possess relevant cybersecurity capacity and digital governance conditions to support data-driven cyber governance. It provides a Cyber-Digital Readiness Index (CDRI), an exploratory proxy for structural preparedness, based on four variables: the Global Cybersecurity Index, the National Cybersecurity Index, the E-Government Development Index, and the Network Readiness Index. An analysis of the CDRI applied to 12 EU member states from Central, Eastern, Baltic, South-Eastern Europe demonstrates that, even though cybersecurity capabilities are critical, they are insufficient in isolation. In addition to cybersecurity capability, structural preparedness is strengthened by digital public-sector maturity, network preparedness, data governance, and inter-institutional interoperability; accountability for the utilisation of algorithmic systems also remains a critical governance issue. The study further indicates that Estonia represents the most robust example in the sample. In contrast, Romania records high cybersecurity scores and low digital development measures, resulting in a large cyber-digital deficit. The study ultimately concluded that structural preparedness for cyber diplomacy in the algorithmic age depends on the combined development of cybersecurity maturity and digital governance capacity.