On Thursday, Judge Tim Gartelmann sealed Titus Emanuel Day's fate, putting him behind bars for at least two years and six months when he will be eligible for parole.
Day's conviction comes after a NSW District Court jury found him guilty of 34 fraud charges in June.
"All (charges) were committed for financial gain though this is inherent in offences of this kind. The offender used the money other than for Mr Sebastian's benefit," Judge Gartelmann said.
Day spent several minutes after being sentenced hugging friends and family members in court before being handcuffed and escorted away by police officers.
The 49-year-old's non-parole period will expire on May 16, 2025.
The funds owed to the pop star encompassed royalties, performance and ambassador fees, including for a wedding in Venice, singing at a Taylor Swift tour, and playing at a New Year's Day Big Bash Cricket event.
In June, Day was found not guilty of a further 13 charges.
He managed the Australian Idol winner via his company 6 Degrees between 2009 and 2017 before the pair's relationship ended acrimoniously.
The entertainer said he was promised a stake in the company as his "foundational client" and a 10 per cent ownership of Solar D, a sunscreen brand Day created.
But Sebastian said this never eventuated before the breakdown in their relationship in 2017.
After trying to recover lost monies, Sebastian filed a civil lawsuit in the Federal Court in July 2018. This case has been put on hold while the criminal proceedings against Day continue.
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