Moideen founded Thumbay Group in 1997. The group operates in various healthcare areas employing 4,000 professionals. It invests $817,000 annually, targeting $2.7 million by 2027 through the Thumbay International Research Grant. In August 2025, the group announced it will launch the Thumbay Psychiatry & Rehabilitation Hospital in Sharjah. Thumbay is also the founder of Gulf Medical University (GMU), and Thumbay Healthcare. GMU has 35 accredited programs, with clinical training at 45 affiliated sites having 3,100 beds anchored by Thumbay Medicity.