Franco Albrecht, 33, was sentenced to five and a half years in prison for “planning a serious act of violence endangering the state” presiding judge Christoph Koller said.
The trial shone a spotlight on neo-Nazi sympathies in the ranks of the German military and the effectiveness of the security services in standing up to right-wing extremism, which is described by the interior ministry as the biggest threat facing the country.
The court heard Albrecht, a father of three, planned the attack while posing as a refugee. Prosecutors backed away from allegations that he hoped to pin his atrocity on Syrians.
Then-justice minister Heiko Maas and a former parliament vice-president, Claudia Roth, were considered to be among his possible targets, the court in Frankfurt heard.
Albrecht, who has a full beard and wears his long hair tied in a ponytail, told the court he deceived authorities at the height of the 2015-16 migrant influx, in which more than one million asylum seekers entered Germany.
Albrecht darkened his skin with make-up to pose as a penniless refugee Christian fruit seller from Damascus called David Benjamin, and for 15 months he hoodwinked immigration officials, despite speaking no Arabic.
“Neither Arabic nor details about my story were necessary,” Albrecht testified, describing his conversations with immigration authorities.
Albrecht, the son of a German mother and an estranged Italian immigrant father, was arrested in 2017 while trying to retrieve a Nazi-era pistol he had hidden in a toilet at Vienna's international airport, and his fraud was discovered when his fingerprints matched two separate identities.
The court found that Albrecht planned to use the pistol and other weapons and explosives he had taken from the German army for an attack.
Soon after his arrest, then defence minister Ursula von der Leyen said Albrecht's case pointed to a much larger “attitude problem” in the German military.
Her successor Annegret Kramp-Karrenbauer ordered the partial dissolution of the KSK commando force in 2020 after revelations that some of its members harboured neo-Nazi sympathies.
Albrecht, who repeatedly expressed anti-Semitic, racist and hardline nationalist views before the court during his trial, testified that then-chancellor Angela Merkel had failed to uphold the constitution by welcoming the refugees.
His lawyers had called for a suspended sentence based solely on weapons law violations.