Blackburn began playing competitive football in the under-9s division for the Beaconsfield Junior Football Club. 2011 saw her named player of the carnival at the national under-18 championships. In 2013, she was the captain of the Victorian side at the under 18 championships, where she was named the competition's best-and-fairest player. She was awarded under 18 All-Australian selection in 2011, 2012, and her final year of eligibility in 2013. She attended high school at Hallam Senior College in Melbourne's outer east. Blackburn played state football for in the VFL Women's. She was drafted by Melbourne with the thirteenth pick in the inaugural women's draft in 2013 and represented the club in the women's exhibition games between 2013 and 2016. Over this time she averaged 20 disposals per match for the club. In July 2016, Blackburn was signed by the – the team that she played against in all of the exhibition matches – as one of two marquee players ahead of the inaugural AFL Women's season.
AFL Women's career
Blackburn was announced as a member of the Bulldogs' inaugural four-woman leadership group in late January 2017. Blackburn made her debut in round 1, 2017, against at Whitten Oval. She was named among the Bulldogs' best, recording twelve disposals and kicking her first league goal in the match. In round 3, Blackburn was named the Bulldogs' best, recording a team high twenty-six disposals and six tackles for the match. Blackburn was highlighted as "Player of the Week" by the AFL Players Association for her round 5 performance in the 2017 AFL Women's season. At the end of the season, Blackburn was second in the competition for kicks, one behind Melbourne's Karen Paxman. Teammates also spoke highly of her leadership after she captained the team for majority of the season, with captain Katie Brennan injured. At the end of the 2017 season, Blackburn was nominated by her teammates for the AFL Players' Most Valuable Player Award and was listed in the 2017 AFL Women's All-Australian team. In May 2017, she was announced as the co-winner of the inaugural Western Bulldogs best and fairest award alongside Emma Kearney. The Western Bulldogs signed Blackburn for the 2018 season during the trade period in May 2017. On 2 September, Blackburn played for Victoria in the inaugural AFL Women's State of Origin match, where she was named among Victoria's best players with three goals. In round 4 of the 2019 season, Blackburn was knocked out in a collision and stretchered off the ground in a neck brace. Leading into the 2020 season, womens.afl journalist Sarah Black named Blackburn at no. 10 on her list of the top 30 players in the AFLW. Despite suffering a hand injury in a practice match, she was able to play in round 1, and was selected in womens.afls Team of the Week for that round. Blackburn was selected in the initial 40-woman squad for the 2020 AFL Women's All-Australian team, and was also selected in the AFL Players Association's 2017–2019 retrospective AFL Women's 22under22 team.
