Knight joined the Green Party of England and Wales in November 2014. She was the chair of LGBTIQA+ Greens between 2015 and 2017. Challenor became the party's equality spokesperson in 2016. According to the Green Party, Knight was the only trans spokesperson for a UK political party. In April 2017, Knight helped co-found the Global Greens LGBT+ Network alongside colleagues from Die Grünen, Groen, Taiwan Tree Party, and Taiwan Green Party. In July 2017, Knight was the Green candidate for Coventry South. She received 1.3% of the vote share, with 604 votes. Knight stood for Coventry City Council elections as a member of the Green Party in February 2016 and May 2016. She stood in a May 2018 local election. She was not elected. Knight stood in the 2018 party election to be deputy leader, which closed at the end of August. In August 2018, Knight's father David Challenor was sentenced to 22 years in prison for raping and torturing a 10-year-old girl in the attic of the home shared by him, Aimee and Tina Challenor. Knights's father had been reported to the police in 2015 and charged in November 2016. Following this, Knight chose her father as her election agent for the 2017 general election and also the 2018 council elections. Knight had given her father's name as "Baloo Challenor" on campaign materials, later commenting that he was known locally by this nickname. After her father's sentencing, Knight – who insisted she did not know the allegations against her father in full – stood down from the Green Party's deputy leadership election. Knight was consequently suspended from the party on a no-fault basis, and the party launched an inquest into possible safeguarding failures as David was allowed to act as Aimee's election agent after having been charged. In September 2018, Knight resigned from the Green Party citing transphobia however Knight continued to cooperate with the inquest. The inquest by Verita found in January 2019 that she had committed a "serious error of judgement" in appointing her father as her campaign manager. The report also said that the Green Party, who were told by Knight that her father had been arrested but not that he was a party member, could have done more to investigate the matter. In October 2018, she joined the Liberal Democrats, becoming the Diversity Officer of her local party. She was suspended from the Liberal Democrats in July 2019, after tweets appeared on her partner's account admitting to having sexual fantasies involving sex with children. Knight said that her partner's account had been hacked.
In 2015, Knight was the LGBTQ Officer for Henley College Coventry; she protested the college's censoring of websites such as Birmingham Pride, which were considered "Gay or Lesbian or Bisexual Interest" by the college web blocker. Knight was an organiser of Coventry Pride in 2016 and 2017. After a Transport for London helpline employee told Knight that she "didn't sound like a Miss", she successfully campaigned to get TfL to investigate the incident and to use gender-neutral language in announcements, avoiding phrases such as "". In May 2018, the BBC published an article that quoted writer Miranda Yardley describing Knight as a "man". Knight said that the BBC did not contact her about the article before its publication, though following readers' complaints she was asked to comment, and her response was added to the article. Knight was a member of the Trans Advisory Group for Stonewall, Britain's largest LGBT charity. She resigned in the summer of 2019 stating there was a "hostile environment towards trans people in the UK" and that she was concerned for her mental health and safety.