During the 2006–07 Australian summer, Duffin was selected for the national youth team to play against New Zealand A, where she had more success as a leg spinner than as a batter.
In the final match of the series, she took 6/28 in a 22-run defeat.
At the start of the 2008–09 season, Duffin played for an under-21 Australian team in a series against India.
She made 60 of the team's 149 all out total in the second-last match, then delivered an unbeaten 79 in the team's winning score of 5/156.

On 1 February 2009, Duffin made her international cricket debut, playing an ODI against New Zealand at Cobham Oval.
Coming in at seven in the batting order, she made 16 from 35 balls in a two-wicket loss.
On 15 February, Duffin made her T20 International debut at the Sydney Cricket Ground, also against New Zealand.
She was not required to bat or bowl in a rain-shortened match that Australia won by nine wickets.

Duffin was selected in Australia's squad for the 2009 Women's Cricket World Cup on home soil.
She played six of a possible seven matches and scored 81 runs at an average of 16.20, with the hosts finishing in fourth place.
Duffin was then selected for the 2009 World Twenty20 in England.
She only played one game and Australia were eliminated in the semi-finals.
During the 2006–07 Australian summer, Duffin was selected for the national youth team to play against New Zealand A, where she had more success as a leg spinner than as a batter. In the final match of the series, she took 6/28 in a 22-run defeat. At the start of the 2008–09 season, Duffin played for an under-21 Australian team in a series against India. She made 60 of the team's 149 all out total in the second-last match, then delivered an unbeaten 79 in the team's winning score of 5/156.
On 1 February 2009, Duffin made her international cricket debut, playing an ODI against New Zealand at Cobham Oval. Coming in at seven in the batting order, she made 16 from 35 balls in a two-wicket loss. On 15 February, Duffin made her T20 International debut at the Sydney Cricket Ground, also against New Zealand. She was not required to bat or bowl in a rain-shortened match that Australia won by nine wickets.
Duffin was selected in Australia's squad for the 2009 Women's Cricket World Cup on home soil. She played six of a possible seven matches and scored 81 runs at an average of 16.20, with the hosts finishing in fourth place. Duffin was then selected for the 2009 World Twenty20 in England. She only played one game and Australia were eliminated in the semi-finals.
Jess Duffin