Paula Romano, 34, stabbed her boyfriend Julio Cesar Vittoria, 62, 24 times while he was naked and tied up in July 2014.
She stole 20,000 ARS (£1,045) from the ice cream shop owner before fleeing the scene in Buenos Aires, Argentina.
The businessman was later found dead with a rope around his neck, his hands tied and stab wounds by his horrified son.
His body was discovered at a property in the neighbourhood of Flores, in the capital city of Buenos Aires.
Romano was eventually caught by police after a 15-month police investigation, and has now been sentenced to life in prison.
Prosecutor Carlos Gimenez Bauer said of the crime: ‘Romano started a sex game in which the man was naked and had his hands tied with a rope around his neck.
‘Once he was like this, she stabbed him 24 times and stole the money. She left the place and ran away.’
The couple had started their relationship in 2003, when she was working as a waitress in a bar that her victim owned.
But the court in Buenos Aires heard that Romano was only ever interested in Vittoria’s money.
Bauer said: ‘Both had an interest in the relationship: one was economical by the part of Romano and the other was more intimate, for Julio’s part.’