The 35-year-old, who worked in commercial property law before her election to parliament in 2017, was jailed for perverting the course of justice last year by claiming someone else was driving her car.
A number of allegations were found proven by a misconduct tribunal on Tuesday, meaning she can no longer practise as a regulated solicitor.
Edward Nally, chairman of a three-member panel at the Solicitors Disciplinary Tribunal in central London, said: "As a parliamentarian makes the law so a solicitor must uphold the law and rule of law, and sadly in this case Ms Onasanya has failed in those duties.
"We must strike off Ms Onasanya from the roll of solicitors."
The tribunal found she acted dishonestly, failed to act with integrity and failed to behave in a way that maintains the trust the public places in her.
Mr Nally went on: "That conviction we are aware has led to disastrous consequences for Ms Onasanya both personally and professionally.
"As a solicitor there are professional consequences that follow from a proven act of dishonesty that has been found by a jury after trial."
The University of Hertfordshire graduate was also ordered to pay £6,562 to cover the costs of the prosecution by the Solicitors Regulation Authority (SRA).
The SRA had originally applied for £22,762 after saying the case took 40 hours of preparation, but Mr Nally reduced it after saying he had "anxiety about the numbers of hours that have been claimed".
Ms Onasanya served 28 days of a three-month prison sentence and continued to sit as an MP and receive her £77,379 salary, despite being expelled from the Labour Party.
She lost an appeal against her conviction in March.
In mitigation, Ms Onasanya had told the panel she was "pursuing avenues to clear my name", adding: "I maintain that I did not do an act tending or intending to pervert the course of public justice."
She also added the speeding incident did not have a "negative effect" on anybody.
Ms Onasanya, who was supported at the hearing by her mother Paulina, declined to speak to reporters afterwards.
The devout Christian qualified as a solicitor in 2015 but stopped practising in 2017 when she was elected for Labour in Peterborough by a small majority in one of the shock results of the snap election.
But within months of taking her seat, she colluded with her brother Festus after her Nissan Micra was clocked speeding at 41mph in a 30mph zone.
She was sent a notice of intended prosecution to fill out, but it was sent back naming the guilty driver as Aleks Antipow, an acquaintance of her brother, who was away visiting his parents in Russia.
Festus Onasanya, 34, from Cambridge, was jailed for 10 months after he admitted three counts of perverting the course of justice over speeding.
Labour's Lisa Forbes is now the MP for Peterborough after winning a by-election in June.
Of Nigerian descent, Ms Onasanya was born in Cambridge, and has revealed that she suffers from multiple sclerosis.
She was the second MP in recent years to end up in court for perverting the course of justice in an apparent effort to avoid speeding points on their driving licence.
Liberal Democrat minister Chris Huhne was sentenced to eight months after pleading guilty in 2013.
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