Law Wan-tung -- who had faced a maximum sentence of seven years -- "showed no compassion" to Erwiana Sulistyaningsih and other domestic staff, said judge Amanda Woodcock in handing down the sentence.
Law saw her staff as "people that are beneath her" said Woodcock.
Of Sulistyaningsih's treatment she added: "She was given little rest, sleep and nutrition which left her a shadow of her former self."
Woodcock called for an investigation by Hong Kong and Indonesian authorities into the workers' conditions.
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During the six-week trial, prosecutors said mother-of-two Law, 44, turned household items such as a mop, a ruler and a clothes hanger into "weapons" against her maids.
Law was convicted on 18 of 20 charges laid against her, including grievous bodily harm, assault, criminal intimidation and failure to pay wages.
"It is regrettable that this conduct is not rare and sadly is often dealt with in the criminal courts," said Woodcock.
Woodcock also highlighted the "significant fees" charged to domestic helpers by agencies in their home countries and deducted from their Hong Kong salaries.
"There must be an element of exploitation here... The domestic helper becomes trapped when they are unhappy, but cannot leave or change employers because the debt needs to be paid off," she said.
Wearing a T-shirt emblazoned with her own face and the word "justice" Sulistyaningsih remained expressionless as the sentence was read out -- she had said that she hoped Law would receive the maximum term.