Rianna Jarrett’s first experience of football came with North End - despite not having a girls' team for her to play with - before she briefly represented Curracloe, the Wexford League team in the FAI Senior Cup and then progressed to Wexford Youths.

Rianna won the Women's National League Player of the Year in 2019 following a superb season with Wexford, where she was overall top scorer and also won the FAI Women's Cup.

On 23 January 2020, Jarrett signed a six-month contract with English FA WSL club Brighton & Hove Albion and is currently with the London City Lionesses for the 2021/22 FA Women's Championship Season.

In 2010, Jarrett was a member of the Republic of Ireland U-17 squad who were runners-up in the 2010 UEFA Women's Under-17 Championship and quarter-finalists in the 2010 FIFA U-17 Women's World Cup.

Jarrett won her first cap for the senior Republic of Ireland national team in March 2016, in a 1–1 draw with Italy at the 2016 Cyprus Cup. The forward netted her first senior international goal in a home win over Ukraine in 2019 and has won 16 caps for Ireland in total so far.