Strawberry (Fragaria ananassa Duch) is one of Egypt's and the world's greatest for business, nutritionally, and health-wise temperate fruit crops. Botrytis cinerea caused one of the most common types of grey mould, causes detrimental diseases impacting strawberry plants, resulting in economic losses in strawberry productivity. This study examined the effectiveness of some biological agents, such as Trichoderma album, T. atroviride, T. hamatum, T. harzianum and Blight stop (T. harzianum, 30x106 spores/ml), in vitro for suppression of B. cinerea linear growth. The most effective treatment was T. atroviride, which significantly decreased the mycelial development of B. cinerea to 90.83%, and then T. harzianum (89.50%), on average. Contrary to this, T. hamatum had the least effect, with an average reduction in fungal growth of 81.33%. All tested biocontrol agents significantly decreased the disease incidence and severity of B. cinerea in strawberry cultivars compared to untreated plants under field conditions during the two seasons 2021/22 and 2022/23, however, T. atroviride showed the best efficacy, followed by T. harzianum. All of the biological control treatments that were investigated led to a significant rise in the values of total soluble solids (TSS), total acidity, ascorbic acid, total chlorophyll, sucrose (%), total phenol and increased strawberry yield during the two seasons. The research was done to identify the best bioagent for protecting strawberry plants from B. cinerea fungal diseases.