Hiemstra joined Uber in September 2015 and assumed his current position in 2022. In June 2024, Uber announced a partnership with the Al-Futtaim Electric Mobility Company in the U.A.E. to offer Uber drivers electric and plug-in hybrid vehicles. In June 2023, the company signed an agreement with Saudi Arabia Railways to launch reservation services, allowing passengers to pre-book Uber Reserve rides to and from railway stations across six cities. Hiemstra was previously general manager for Uber in sub-Saharan Africa.