Environmentally friendly routes from “Power‐to‐X” (P2X) technologies to sustainably harvest and store renewable energy with net‐zero CO2 emission are imperative. The concept of P2X relies on (photo)electrolysis of earth‐abundant molecules into value‐added products. For practical utilization, engineering robust, active, albeit inexpensive (photo)electrocatalysts via industrially compatible technologies is indeed crucial. In this context, flame spray pyrolysis (FSP) stands as an emerging approach for one‐step synthesis of ready‐to‐use (photo)electrocatalysts with production rates of Kg h‐1 in lab‐scales. While features of FSP to engineer nanomaterials have been summarised, there is a need for more critical discussions on key factors, modulating properties of flame‐made catalysts. Therefore, this review article will first provide an overview about the concept of the P2X and catalyst development strategies. Unique characteristic of flame‐synthesized nano‐catalysts including compositions, fractal morphologies, defects, and active sites will be then critically discussed. Furthermore, a potential of FSP as an electrode‐assembly technique for one‐step preparation of catalysts on gas diffusion layers for industry‐relevant electrolyser testing will be presented. Finally, perspectives on challenges and opportunities of FSP for renewable energies will be raised. This will provide insights into the versatility and commercial viability of the FSP route for engineering novel nanostructured catalysts for renewable energy applications. This article reviews the versatility and capability of the flame spray pyrolysis (FSP) in nanocatalyst design and preparation for Power‐to‐X applications. FSP allows modulation of material varieties, chemical compositions, nanostructured morphologies, and defects. Moreover, ready‐to‐use catalysts can be synthesized and assembled directly on gas diffusion layers by one‐step synthesis without nonconductive binders and ink‐based assembly in a time‐frame of seconds.