Protein farming, or molecular farming, is an innovative approach that utilizes plants/animals/microorganisms as biofactories to produce valuable pharmaceutical proteins, antibodies, vaccines, and other high-value bio-active molecules. This emerging field has gained significant attention due to its potential to address the growing demand for affordable and scalable biopharmaceutical production platform. Correspondingly, plants offer several advantages over traditional expression systems, including low production costs, scalability, ease of manipulation, and reduced risk of contamination by pathogens. This review provides an overview of principles underlying protein farming in plants (P-farm), including the identification and selection of host, optimization of transgene expression, and downstream processing techniques for protein purification. It also discusses recent advancements in plant biotechnology and the development of transient expression systems to use genetically modified plants (transgenic plants) in the enhancement of protein production. Additionally, the potential applications and challenges associated with molecular farming in plants are considered, including prospects of commercialization and novel opportunities to meet the growing demands of global healthcare markets.