Stuart Prior, who recently won seats on Essex County Council and Rochford Borough Council, resigned shortly after controversy over alleged posts relating to him.
The party also confirmed it had revoked his membership.
Charges over extremist and racist posts online
According to the campaign group Hope Not Hate, Pryor was linked to social media posts that included statements describing white people as a “master race” and suggesting they have “bigger brains.”
Other comments allegedly made by him included abusive and inflammatory language targeting Muslims and ethnic minorities.
When Pryor faced the media, he reportedly denied recalling the posts and refuted the claims, saying: “I wouldn’t have said that.”
Reform Britain’s response: resignations and sackings
A spokesman for Reform UK said Pryor informed the party that he was resigning for “personal reasons”, adding that his membership had been revoked with immediate effect.
Local councils confirmed his resignation from two elected positions, triggering preparations for by-elections in the affected constituencies.
His resignation comes just days after the Reform Party made significant progress, wresting control of Essex County Council from the Conservatives with a majority.
Pryor received around 40% of the vote in his district, making his sudden exit particularly damaging to the newly formed council leadership.
The incident is part of a wider wave of scrutiny involving several newly elected cross-party MPs, with many facing accusations of racist, anti-Semitic or extremist online content.
Investigations and suspensions were reportedly carried out by different committees as political parties scrambled to deal with the growing backlash over candidates’ past social media activities.
Essex County Council and Rochford Borough Council have both confirmed they are co-ordinating the organization of the by-election and details are expected to be released soon for affected residents.