Widad Babiker, who is believed to be in her late 40s, is Al Bashir's second wife.
She can appeal the ruling within two weeks.
The officials said Babiker could not convincingly explain to the court how she came to possess a “fortune, properties and precious stones”.
The court also ruled to confiscate funds she held in two accounts at a local bank, they added.
Corruption allegations have swirled around Al Bashir's second wife since the dictator was ousted in 2019 following a popular uprising.
Al Bashir himself was convicted on corruption charges in 2020 and sentenced to two years in a correctional facility.
Babiker married Al Bashir in 2002, less than a year after her first husband, army general Ibrahim Shamseldeen, was killed in a plane crash.
Al Bashir is currently on trial for overthrowing a democratically-elected government when he seized power in a 1989 coup.
He is facing a separate trial for the shooting deaths of protesters during the December 2018 to April 2019 uprising that forced the military to topple him.