Blackwell was selected for the Black Ferns 2017 Rugby World Cup squad.[6][7] They won their fifth World Cup title after defeating England 41–32 in the final.[8][9]
2018
In 2018, Blackwell was one of 28 players who became the first women in New Zealand to receive professional contracts.[10] She scored a try in the second Test of the Laurie O'Reilly Cup against the Wallaroos at Eden Park.[4]
2019–20
Blackwell was part of the winning team of the 2019 Super Series at San Diego.[11] She scored tries against Canada, and the United States at the tournament.[4] A month later, she scored a try in the second Test of the O'Reilly Cup against the Wallaroos in Auckland.[4] She captained the Black Ferns against a New Zealand Barbarians side in 2020.[12][3]
2021–22
Blackwell played for the Blues against the Chiefs in the first-ever women's Super Rugby match in New Zealand on 1 May 2021.[13][14] She was part of the Black Ferns disappointing end-of-year tour of England and France in October and November.[15]
In 2022, she was one of 29 players contracted to the Black Ferns.[18] She featured in the Blues Women's 0–35 thrashing by the Chiefs Manawa in the final round of the Super Rugby Aupiki competition.[19][20]