As Gemma Flynn, she has competed for the
New Zealand women's national field hockey team (the
Black Sticks Women) since 2008, including for the team at the
2008 and
2012 Summer Olympics,
2016 Summer Olympics and at the
2010 and
2014 Commonwealth Games. In 2009 she was nominated for the
FIH Women's Young Player of the Year. At both the 2012 and 2016 Olympics, her team lost the bronze medal game and thus came fourth. She was part of the team which made it to the final game of the FIH World League in 2015, but the team lost 5–1 against Argentina. Following the 2016 Summer Olympics, she took an extended break from hockey and later decided to retire. She came out of retirement in November 2019. In February 2020, she reached her 250th cap for the national team. Gemma McCaw had intentions of competing again in the
2020 Summer Olympics in
Tokyo but with it being delayed due to the
COVID-19 pandemic decided against it. ==Outside hockey==