Upton started playing field hockey at Crescent College and then subsequently with Catholic Institute. She helped Crescent College win two Munster Schools Junior Cup and two Senior Cup titles. She also captained the Crescent College team. She helped Catholic Institute challenge for Munster club honours.[5][10][11]
Munster and Ireland youth player of the year in 2011
Together with Emily Beatty and Katie Mullan, Upton represented Ireland at the 2010 Youth Olympic Games.[5][7][32]Graham Shaw first included Upton in an Ireland squad in 2015. In January 2016 she was also included in a squad for series of away games against Spain. However, on both occasions Upton had to withdraw from the squads because of injuries.[21][33] She eventually made her senior debut on 6 November 2016 against Scotland.[7][11][34] In January 2017 she was a member of the Ireland team that won a 2016–17 Women's FIH Hockey World League Round 2 tournament in Kuala Lumpur, defeating Malaysia 3–0 in the final.[35] Upton scored four goals in the tournament. On 17 January 2017 she scored her first senior Ireland goal in a 10–0 win against Hong Kong. On 19 January 2017 she scored a hat-trick in a 10–0 against Singapore.[18]