In 2016 she joined the Liberal Democrats, shortly after the 2016 European Union referendum claiming it was the "only true pro-remain party". In November 2018, she was selected as the Liberal Democrat candidate for the 2020 London mayoral election. In November 2019, Benita said that money from unused Oyster cards should be used to help fight homelessness. Benita launched her campaign for the 2020 London mayoral election on 13 February 2020. She said she wanted to legalise cannabis in London in a bid to tackle rising levels of knife crime. She stated she would like to see pilots for legal regulated cannabis across London in order to remove power and money from gangs, free up police time to tackle serious crimes, and raise millions of pounds in tax, which could be invested in youth services and support those addicted to harder drugs. She has also pledged to cut violent crime, cut air pollution, declared an aim to reach zero-carbon by 2030, and reopen closed police stations.