Tessa Diphoorn conducts research and teaches at the Department of Cultural Anthropology at Utrecht University. Her research focuses on policing, security, violence, and power and she analyses these societal and conceptual issues from an anthropological lens. Her ethnographic research is primarily based in South Africa and Kenya. 

She is also one of the co-founders and (current) coordinators of the Institutions for Open Societies and Utrecht Centre for Global Challenges Contesting Governance Platform.

Since September 2021, she is participating in an international project on Algorithmic Policing, wherein she will focus on the role of algorithmic governance in the private security industry in South Africa. Between May 2017 and February 2020, she worked on a NWO-funded (Veni) research project titled 'Policing the Police in Kenya: Analysing state authority from within', wherein she analysed the various ways in which police (mis)conduct is documented and regulated in Nairobi, Kenya. Before that she conducted extensive ethnographic research about private security in South Africa and her book, Twilight Policing. Private Security and Violence in Urban South Africa, has been published with the University of California Press (2016). She also worked as a post-doctoral researcher at the University of Amsterdam, where she conducted research on public-private security assemblages in Kenya, Israel, and Jamaica.

Tessa Diphoorn is the co-host and co-founder of the podcast series Travelling Concepts on Air. Together with Brianne McGonigle Leyh, they explore the notion of travelling concepts in academia.