The 22-year-old had been facing up to 30 years in jail but could be free in about two-and-a-half years under the deal struck between her lawyers and the prosecution.
Sainsbury pleaded guilty to drug trafficking charges after being caught with 5.8kgs of cocaine hidden inside 18 headphone boxes as she tried to leave Bogota's airport in April.
Her mother Lisa Evans flew from her home in Adelaide to be with her daughter as the judge handed down his decision in a closed court hearing in Bogota on Wednesday, local time.
Sainsbury's lawyer Orlando Herran told reporters outside the court that the judge had taken into account her claims that she was forced to carry the drugs because of violent threats made against her family.
"He was taking into account all the stories related to the case in which she was subjected to lots of threats by third parties," he said through a translator.
"She's lucky because the amount of the drugs was very big."
Mr Herran said he intends to appeal the $US90,000 fine as Sainsbury is unable to pay it.
He added that Sainsbury's sentence could be reduced if good behaviour is taken into account, along with the six months she has already served, meaning she could be released in April 2020.
Sainsbury didn't make any comment to a large media contingent waiting outside the court as she left by bus to return to prison.
In an interview with the Nine Network's 60 Minutes program in September, Sainsbury told of how she landed in trouble in Colombia after thinking she had accepted a job as a legitimate courier transporting documents for $10,000 plus flights, but plans changed at the last minute.
She was sent to Colombia where a "mastermind" known only as Angelo threatened via WhatsApp to kill her mum, sister and fiance if she did not transport his drugs.
In August, a Colombian judge threw out the original plea deal Sainsbury's lawyer struck with prosecutors, in exchange for information on the drug ring she was involved with.
At the time, the judge said he was unable to accept the deal because of Sainsbury's surprise claims about being forced to carry the drugs because her family had been threatened.
Her lawyers and prosecutors struck a new plea deal in October.