[5] After four more fights in 2018—PTS wins over Borislava Goranova in February and Bojana Libiszewska in April,[6][7] and stoppage wins over Bec Connolly in October and Feriche Mashauri in December[8][9]—she faced undefeated Commonwealth super-lightweight champion Nina Bradley on 8 March 2019, at the Barnsley Metrodome in Barnsley, with the vacant WBC International female lightweight title on the line.
The fight was televised live on Sky Sports as part of the undercard of Katie Taylor's world title bout against Christina Linardatou.
[15] Harper successfully retained her IBO title via unanimous decision (UD) over ten rounds, with the judges' scorecards reading 99–91, 99–92, and 97–93.
In the post-fight interview, Hearn announced that terms had been agreed for Harper to challenge reigning champion Eva Wahlström for the WBC female super-featherweight title in early 2020.
[22] In the second defence of her WBC title and fourth of her IBO, Harper faced former European female super-featherweight champion Katharina Thanderz on 14 November 2020.
The bout served as part of the undercard for Katie Taylor's world title defence against Miriam Gutiérrez at The SSE Arena in London.
Thanderz suffered an injury to her nose after an accidental clash of heads in the ninth round before being hurt with a punch to the body, causing her to bend over in pain.
[26] On 23 March 2024 in Sheffield, England, Harper challenged Sandy Ryan for her WBO welterweight title, but lost the fight via fourth-round RTD.