Alice Cutter, 23, along with ex-partner Mark Jones, 25, Garry Jack, 24, and Connor Scothern,18, are facing up to ten years in jail each after being convicted of being members of banned National Action.
They were part of the proscribed right-wing group and intended to wage a "holy war" against black people, Jews, Asians and homosexuals.
Cutter and Jones, of Sowerby Bridge denied being part of a proscribed organisation alongside Jack, of Shard End, Birmingham, and Scothern, of Nottingham.
Today (Thurs) the four were found guilty by a jury who deliberated for less than nine hours hours following a trial at Birmingham Crown Court.
The extremist group was outlawed following National Action members' celebration of the murder of MP Jo Cox by extremist Thomas Mair on June 16, 2016.
The court was told how Alice Cutter and Mark Jones formed a relationship in 2016, later moving in together and getting engaged.
Both went on to use the encrypted chat platform Telegram with other members of National Action, before and after the ban.
Cutter was found to have made a series of racist and offensive posts, including against black people, Jews and the disabled.
On June 24, 2016, National Action staged a beauty contest titled Miss Hitler 2016.
Cutter entered and billed herself "Buchenwald Princess" - after the German concentration camp where thousands of Jews were slaughtered during the Second World War.
She had entered the competition in a bid to recruit more members to the extremist group and "raise the profile" of National Action, jurors were told.
The court heard it was "no coincidence" her former fiancé Jones had been pictured doing a Nazi salute in an execution room at the camp just a month earlier.
Jones - who was nicknamed "Grand Daddy Terror" - also took commissions from racists on Instagram to draw offensive images, charging £50 each.
Jurors heard Jones carried on plotting "banner drops, graffiti throw-ups and video promo shooting" with fellow members of National Action after it was banned.
The court heard Scothern joined National Action when he was 15, and continued to message members after it was banned because he was "lonely".
Scothern was found to have a vile meme on his phone showing piles of ash with the words "dead jew child".
The court heard Jack was an "out and out fanatic" who wanted to be part of the National Action "revolution."
When questioned by police, Jack claimed the Donald Trump's description of African countries as "s**tholes" and Mexicans as "rapists" showed these opinions were not unique to National Action.
He also pointed to accusations of antisemitism made against Jeremy Corbyn and the Labour Party, and asked police if Mr Corbyn should also be regarded as a terrorist.
All four defendants denied being members of National Action after it was banned, with Cutter claiming she had never been part of it in the first place.
Prosecutor Barnaby Jameson QC said during the trial: "We are talking about a secretive group of die-hard neo-Nazis with no compunction whatever of obtaining their objectives through terror.
"A group with admiration for Hitler and advocation of the Holocaust. A group with a shared enthusiasm for ethnic cleansing and eradication of the Jews.
"You will be forgiven for thinking that the ideology of Hitler had died out at Nuremberg. You would be wrong.
"For the accused, Hitler's work will always be unfinished. This is a group for which the final solution to the Jewish question remains to be annihilation."
Head of West Midlands Counter Terrorism Unit (WMCTU), Detective Chief Superintendent Kenny Bell said after the verdicts: "National Action is an extreme right wing neo-Nazi group.
"Their ambition is to prepare for a race war by amassing weapons and trying to recruit others by the spread of their extreme ideology.
"Being convicted of membership of this extreme right terrorist group is the same as belonging to other terrorist groups such as Al-Qaeda or Daesh.
"They share a real toxic extreme ideology which is a danger to the public, the same ideology that we have seen manifested in the tragic attack in New Zealand, the murder of Jo Cox MP and the attack at Finsbury Park mosque in 2017.
"This group was amassing weapons and recipes for bomb-making.
"They communicated through secret channels to recruit others to their cause. Left unchecked they presented a real threat to the public.
"We have seen a significant increase of right-wing referrals to our Prevent programme and we will investigate the threat as robustly as we would any other terrorist group, as well as training our officers on the signs to look out for and working with communities to increase awareness.
"Terrorists and extremists use this kind of ideology to create discord, distrust and fear among our communities and we strive to counter this.
"I would encourage people to report hate crime to us and it will be taken seriously."