Despite having no medical background and only a primary level education, Mary Chen's unwavering faith as a devout Christian led her to defy all odds and discouragement from people around her, as she took over a financially troubled hospital at the end of 2010—transforming it into a community-driven, award-winning hospital now known as Beacon Hospital, with its own Cancer Centre of Excellence housing the largest team of cancer specialists in the private sector, alongside with seven other centres of excellence, that include brain and spine, bone and joint, eye, men's health and urology, women's health, health screening and wellness and clinical research.

At the helm of Beacon Hospital, Chen has invested hundreds of millions in state-of-the-art equipment and therapies, later implementing various CSR programmes that saw the hospital providing free and subsidised treatments for low-income cancer patients. Despite the economic setbacks the hospital experienced over the past decade, Chen remains resilient in her commitment to helping underprivileged cancer patients, relieving them from financial burdens while continuing their treatment.

She is known and loved for her approachable demeanour, and often visits patients throughout the hospital, personally checking on their well-being. Recognising patients' concerns about consuming commercially farmed chicken due to the possible association with hormones, antibiotics, and chemical substances, she and the team developed the antibiotic-free and hormone-free 'Beacon Chicken' which became a signature product at Beacon Mart.