With global population growth, escalating ecological pressures, and evolving consumer demands for health-conscious products, traditional animal and plant protein supply models face numerous challenges-including resource scarcity, high carbon emissions, and limited nutritional diversity. The development and application of novel protein sources have become a research focus in biomanufacturing, food science, and biopharmaceuticals. These novel protein sources encompass microbial proteins, plant-based proteins, algal proteins, cell-cultured proteins, and AI-designed artificial proteins, offering advantages such as environmental sustainability, low carbon footprint, and customizable functionality that overcome the limitations of conventional protein production. This article systematically reviews the resource characteristics, development processes, and core technological frameworks of various novel protein sources. It highlights the application of cutting-edge technologies-including AI-based de novo design, precision fermentation, bioextraction, and cell culture-in protein development, analyzes current applications in food, feed, and biopharmaceutical sectors, identifies technical barriers, safety regulations, and industrialization costs, and proposes future research directions. The study aims to provide theoretical insights and technical support for the industrial-scale, high-quality development of novel protein sources.