Isolating fungal endosymbionts is crucial for understanding their roles in various ecosystems, agriculture, and biotechnology. Fungal endosymbionts residing within plant tissues play essential roles in enhancing plant growth, stress tolerance, and disease resistance. However, their isolation presents several challenges, including host specificity, non-culturable nature, and contamination risks. Traditional methods, such as morphological identification, are often supplemented or replaced with molecular techniques, including DNA sequencing of conserved regions like the ITS and 18S rRNA genes, which provide accurate identification of endosymbionts. Recent advancements have enabled the isolation of diverse endosymbiotic fungi, such as Epichloë festucae, Piriformospora indica, Trichoderma harzianum, Fusarium oxysporum, and Penicillium chrysogenum, each of which offers unique benefits, ranging from biocontrol to antibiotic production. This book chapter highlights the importance of combining traditional and molecular approaches to overcome the challenges of isolation, ensuring a deeper understanding of fungal endosymbionts and their potential applications across various fields.