In May 2018, Duffin signed with expansion club North Melbourne as a free agent.
She played across half-back throughout the 2019 AFLW season, managing three games of 20-plus disposals and leading the league in marks for the second time.
Despite having the third-best record in the league, North Melbourne controversially failed to qualify for the four-team finals series due to the competition's conference structure.
Duffin was nevertheless recognised for her dominant season, earning selection in the 2019 All-Australian team.

During the 2019 sign-and-trade period, Duffin was comparatively slow to negotiate a new contract.
On 19 April, North Melbourne announced they had re-signed her for two more years.
However, on 31 December, Duffin announced she was due to give birth within the next six months and would therefore miss the 2020 AFLW season.
In May 2018, Duffin signed with expansion club North Melbourne as a free agent. She played across half-back throughout the 2019 AFLW season, managing three games of 20-plus disposals and leading the league in marks for the second time. Despite having the third-best record in the league, North Melbourne controversially failed to qualify for the four-team finals series due to the competition's conference structure. Duffin was nevertheless recognised for her dominant season, earning selection in the 2019 All-Australian team.
During the 2019 sign-and-trade period, Duffin was comparatively slow to negotiate a new contract. On 19 April, North Melbourne announced they had re-signed her for two more years. However, on 31 December, Duffin announced she was due to give birth within the next six months and would therefore miss the 2020 AFLW season.
Jess Duffin