Yaxley-Lennon, who was jailed for nine months in July after being found guilty of contempt of court, is believed to have told supporters via an affiliated news channel that Mr Johnson's decision to expel 21 Tories who rebelled over Brexit was 'refreshing'.
The co-founder of the English Defence League's thoughts were shared to an official account on social network Telegram. writing: "21 Tory traitors decided to side with Corbyn and the Labour traitors and try and block the Brexit that the majority of people voted for."
Telegram is an app often favoured by far-right figures who have been banned from mainstream social media networks.
Yaxley-Lennon, who has a lengthy criminal history, is banned from Facebook, Instagram, Twitter and Snapchat.
The Telegram message went on:
"Boris sacked them which was good to see! Amber Rudd resigns - who gives a s***. We back Boris, now just get us out of the EU. Labour are crying that Boris is stealing democracy when in fact he is trying to do what the people voted for.
"The very same Labour traitors crying that democracy is being stolen are preventing a general election because they know that the people will vote Boris. #BackBoris"