Hawzah News Agency (London, UK) – "Lutz Bachmann", who has led anti-immigration marches of tens of thousands of people, landed at Stansted airport on Saturday night.
He was detained and subsequently expelled from the UK on Sunday morning.
The Home Office said Bachmann was refused entry on grounds, his presence in Britain was not in the interest of the public good.
"Border Force has the power to refuse entry to an individual if it is considered that his or her presence in the UK is not conducive to the public good," said a spokesperson.
Supporters say Bachmann was due to speak alongside Tommy Robinson – the former English Defence League leader who founded a subsidiary branch of Pegida in the UK – at Speakers’ Corner in Hyde Park on Sunday.
The 45-year-old founded Pegida, which stands for "Patriotic Europeans against Islamization of the West", in October 2014 to demonstrate opposition to plans for 14 refugee centers in Dresden, Germany.
Branded "Nazis in pinstripes", the group has been widely accused of racism, fascism and xenophobia.
Bachmann stepped down from his official role as leader in January 2015 after a picture of him dressed as Hitler surfaced on Facebook – something he dismissed as a "joke". However, he then capitalized on a resurgence of concerns around a migration influx and returned to his post after the outcry had subsided a few months later.
According to the Sachsische Zeitung newspaper, Bachmann has several criminal convictions – 16 burglaries, driving drunk or without a license and dealing cocaine.
In 1998, after Bachmann was sentenced to a number of years in prison, he fled to South Africa but was deported back to Germany.
The decision to bar Bachmann comes after Canadian far-right activist Lauren Southern was detained in Calais and banned from entering the UK earlier in the week.
Ms Southern, who worked for far-right Canadian site The Rebel Media, was held by Border Force in Coquelles on Monday.
Ms Southern, who supported a seaborne mission seeking to hamper the rescue of refugees, claimed British authorities had told her she was "officially banned from UK for racism" after being detained.
"They just locked me out and said 'au revoir' ... Officially banned from UK for 'racism' ... Doing fine though, all the cool people are being banned anyway," the far-right provocateur tweeted.
Writing in a Facebook post last week, Generation Identity, a British white supremacist group, said Austrian far-right activist Martin Sellner and his American girlfriend Britanny Pettibone, who is a YouTuber and author, had been detained by the British Government.
The couple were refused entry at Luton airport on Friday, also on grounds their presence was not conducive to the public good. Mr Sellner and Ms Pettibone were detained and subsequently removed from Britain on Sunday.