Moideen founded Thumbay Group in 1997. The diversified international company operates across various sectors, including healthcare, medical research, and pharmacy. It has a network of healthcare facilities, including 350-bed Thumbay University Hospital, Thumbay Medical & Dental Specialty Centre, Thumbay Hospital Day Care, Thumbay Dental Hospital, Thumbay Physical Therapy and Rehabilitation Hospital, Thumbay Clinic, and Thumbay Clinic ELITE. In 2020, Thumbay University Hospital signed an agreement with Gulf Medical University to implement international-standard academic health centers. In the same year, the hospital announced that it had served four million patients since it was established in 2002.