Secondary school teacher Catherine Lim Joon Thong, 31, pleaded guilty to pulling the hair of Melanie Llanada Tulang and repeatedly hitting her head against a wall in December 2002.
Lim had originally faced five charges amounting to a seven-year prison term and a fine of 5,000 Singapore dollars (US$3,050) for the offenses, committed over a two-week period.
In the mitigation plea, defense lawyer Daniel John said his client, a mother of two, had an "unblemished" record as a teacher of eight years.
"She had great anxiety coping with the demands of teaching," John told reporters outside the court, adding that his client was certified as suffering from "severe depression" and had found the maid’s performance to be inadequate.
Tulang has since been sent back to the Philippines.
Judge See Kee Oon in his verdict said he had little choice but to imprison Lim despite the mitigating factors.
Some 150,000 foreign women, mostly from Indonesia, the Philippines, Sri Lanka and India, work as domestic helpers in Singapore, which has a total population of 4.2 million.