In the context of agricultural advancements, the integration of technology, specifically online marketing channels, remains under-researched, particularly in addressing the training needs of farmers. This study, conducted in three phases in the Lan Saka District, Nakhon Si Thammarat Province, aimed to fill this gap by developing and evaluating a training process tailored to enhance the efficiency of online mangosteen marketing. The first phase focused on the development of a farmer training process. The second phase assessed the effectiveness of this training process. While the third phase involved certification of the training process. The findings of the study revealed that the training process was highly appropriate, based on evaluations of its various stages, from need analysis to follow-up. Post-training, a significant improvement (p< 0.01) was observed in the farmers' achievements in online marketing using smartphones, and their operational capabilities on a Facebook fanpage exceeded 70%, with statistical significance at the 0.01 level. Participant satisfaction with the training was at the highest level. The process was certified by experts, highlighting its accuracy and potential to significantly impact online marketing approaches for farmers. The training was deemed suitable and feasible for practical implementation among diverse groups, including farmers, with an emphasis on the necessity of participants possessing requisite qualifications, particularly in understanding communication technology.