Helen Mary Rosamond, the former chief executive of events and human resources company Human Group, was found to have splashed out millions of dollars in kickbacks to bribe Rosemary Rogers.
Rogers, a highly trusted NAB senior staffer now behind bars, gave evidence of receiving a house, a BMW car, a boat, holidays and other benefits after approving false bank invoices for the businesswoman.
Rosamond, 47, had pleaded not guilty in the NSW District Court to 92 fraud and bribery charges said to have been committed between 2013 and 2017.
On Friday, the jury found her guilty of 21 of 22 charges, after having found her guilty of 69 of 70 charges on Wednesday.
Judge Robert Sutherland commended the jurors on their attention and diligence at the complex trial.
He continued Rosamond's bail but ordered her to report to police daily over the weekend and be subject to a curfew between 11pm and 6am.
He will hear an application to revoke her bail on Monday.
Rogers told the jury she received a prison sentence in December 2020 after pleading guilty to 27 counts of corruptly receiving a benefit and five of obtaining a financial advantage by deception.
She received discounts for pleading guilty and for providing information to authorities.
The Crown contended that Rosamond sent falsified and inflated invoices from Human Group to NAB and paid millions of dollars in kickbacks to Rogers to ensure they were paid.
Rogers, who was authorised to approve payments of up to $20 million, testified to becoming good friends with Rosamond, who did a "great job" at organising events for the bank.
She approved her invoices without enforcing requirements about audits, listing expenses and supplying supporting documents.
The jury heard evidence that as well as paying the kickbacks, Rosamond was getting the bank to foot the bill for her own luxurious lifestyle.
She was said to have bought a Toyota Kluger for her in-laws and a $30,000 fuel bill for a family member's trucking company.
The Crown alleged she also took her own family on a $132,000 holiday to the Rocky Mountains in the US, which was coded as a NAB business trip and drawn down against the bank's prepaid account with Human Group.
Among the largest of the allegedly fraudulent invoices issued was one for $2.2 million.
It was purportedly for "Project Eagle" - the codename for the onboarding of former NSW premier Mike Baird as an NAB executive in 2017 - but instead was to cover a substantial amount for a home Rogers had purchased in Melbourne.
An extra $700,000 went to Rosamond, according to the Crown.
Rogers said she started as a teller at the bank in 1995 and worked her way up to becoming chief-of-staff to NAB's chief executive.
She worked for two men who held that role, from 2009 until 2017 when the bank received an anonymous whistleblower letter about her.
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