Wiesner holds a M.Sc in mathematical statistics from the University of Stellenbosch, and a DPhil in applied statistics from the University of Oxford where he read as a South African Rhodes Scholar. He is affiliated with the Royal Statistical Society as chartered statistician. He worked in bioinformatics, online gaming, credit risk and at a paid search agency before joining Google in their London office as a statistician in 2011. He serves a a selector for the Schmidt Science Fellowship.