Tom Williams is Professor of Haemoglobinopathy Research at Imperial's Institute of Global Health Innovation, from where he is seconded to the KEMRI-Wellcome Trust Research Programme in Kilifi, Kenya. He has been funded by Senior Research Fellowships from the Wellcome Trust since 2005.

His research focuses on the health consequences of specific genetic conditions, particularly those affecting red blood cells. In 2024, he won a 7 year Discovery Award from Wellcome, through which he is investigating the pathophysiology of malaria in carriers of the sickle mutation. He is also the Principal Investigator of an 1800 patient Joint Global Health Trials funded trial in which he is investigating pragmatic treatments for the management of sickle cell disease in Africa (H-PRIME; ISRCTN15724013). He is the Principal Investigator for Kenya on an NIH funded Phase II trial of hydroxyurea use in children with sickle cell disease in Kenya, Uganda, Angola and the DRC (REACH: Realising Effectiveness Across Continents with Hydroxyurea), and a co-investigator on other trials and research projects on malaria and other neglected diseases throughout Africa.