Using additive manufacturing to fabricate conformally cooled die inserts for mass production processes such as high-pressure die casting or injection molding is very attractive due to the high design freedom and the small quantity needed for each part. However, there is a great need to develop novel hot-working die steels tailored for laser powder bed fusion (LPBF). Conventional hot-working die steels (1.2343, 1.2344, 1.2365) possess a carbon content of approx. 0.25 wt.% to 0.6 wt.%, resulting a poor weldability, respectively printability. Often, hot and cold cracking occurs using medium carbon hot working die steels, particularly in industrially relevant component sizes. Until now, remedies to avoid cracking are mainly process-related, e.g., including optimized scan strategies to manipulate melt pool shape, respectively, the proportion of solidification type, increased preheating temperature, and reduced laser energy input to decrease thermally induced stresses. As a substitute for conventional die steels, maraging steels are also used for LPBF printing of die inserts. Latter steels possess excellent printability yet drastically reduced thermal conductivity, leading to increased thermal stresses at the die insert surface. Thus, LPBF-tailored die steels are in high demand to industrialize this technology. In this study, novel die steels are mechanistically designed using the CALPHAD method, fulfilling the property requirements (1) a high thermal conductivity (>35 W/mK @450°C), (2) reasonable hardness (42-48 HRc), (3) acceptable tempering resistance (>500°C), and excellent printability. Detailed LPBF-printing and experimental characterizations confirm the computational results.