Laura Matthews splashed out on a £42,258 BMW, spent £26,000 on horses and equine products and purchased £38,000 worth of treats through Pay Pal.
Newcastle Crown Court heard the 32-year-old stole the cash over a six-year period between May 2013 and July 2019, when she was employed on the finance team at the bank, in Newcastle, by simply transferring it into her own account.
Prosecutor Kevin Wardlaw told the court: "What the defendant had been doing was, quite simply, transferring money into her own personal accounts.
Sunderland at Wembley: Fans raise 'virtual tip jar' fundraising target to thank staff at Covent Garden pub after smashing original total
Sunderland at Wembley: London pub chain Fuller’s heaps praise on Sunderland fans after Wembley weekend - after welcoming Peter Reid to one of its bars
Sunderland at Wembley: 'We're looking forward to welcoming them back next year' says brewery boss as fans' behaviour in Trafalgar Square praised
19 Sunderland locations hosting Queen's Platinum Jubilee street parties
So what was so good about Trafalgar Square? Sunderland shows football is a game that can still be great
"She falsified records to cover up what she was doing. On paper, everything reconciled, in reality the shortfall had been paid into her various accounts."
The court heard Matthews had transferred cash into four of her own accounts, during 49 fraudulent transactions, ranging from £5,700 up to £141,600 in onego.
Mr Wardlaw added: "It is apparent from the inquiries made by the police financial investigator that whatever the motivation was for offending at the outset, it soon became a way of funding an extravagant lifestyle.
"There was the high value car, horses, she was, in effect, living the high life and enjoying the benefits of the money she obtained."
The court heard all of the money she stole has now "gone".
The court heard Matthews' dishonesty was uncovered when she took some time off and her replacement at work noticed a discrepancy in a ledger.
When Matthews became "aware of conversations going on at work" about her she left her job and handed herself in to the police.
She initially admitted taking around £34,000, which she said was to pay off debts, but a full investigation by Virgin revealed the shocking extent of thedishonesty.
Matthews, of Rosecroft, Pelton, County Durham, pleaded guilty to theft of £1,309,719.67 belonging to Virgin Money.
She also admitted a charge of transferring criminal property.
Harbinder Lally, defending, said Matthews, who had debts including payday loans, which were paid off, is "deeply ashamed, embarrassed and describes it as a horrendous crime".
Mr Lally said Matthews was a "loner" who lived with her parents and added: "She didn't have any friends, it appears she tried to buy friendships."
Mr Lally said the majority of the money went on Matthews' "love for horses" and she did not splash out on clothes, social nights and hotels.
Mr Recorder Andrew Latimer sentenced Matthews to four years and nine months behind bars.
The judge told Matthews she was living "well in excess of your honestly gained means" and told her: "You covered your tracks of one offence to enable you torepeat it and not get caught".
Prosecutors have launched proceedings under the Proceeds of Crime Act which means any assets Matthews has could be seized.