Bell finished fifth at the 2021 British Athletics Championships event, which doubled up as the Olympic trial event. She was not initially selected for the delayed 2020 Summer Olympics, when the athletics squad was announced in June 2021. On 8 July, Bell was selected for the 800 metres event at the Games, replacing Laura Muir, who had qualified for the event but later decided not to compete as she wanted to focus on the 1500 metres race. In the Olympic final, Bell finished seventh in a personal best time of 1:57.66.