Moideen founded Thumbay Group in Ajman, UAE, in 1997, a conglomerate spanning healthcare, medical education and research, diagnostics, retail, hospitality, and technology. The group employs 3,500 people and has eight hospitals as of May 2026. Its healthcare division includes Thumbay University Hospital, Thumbay Day Care Hospital, Thumbay Clinic network, Thumbay Labs, and Thumbay Pharmacies, among others. In February 2026, Thumbay launched Thumbay Medicity Dubai, a hospital and academic district in Al Qusais.