Liu Xitang, 35, pleaded guilty to one count of theft in court on July 30 after committing the crime on June 2, The Straits Times reported.
Liu had entered Malaysia from China on May 31 and was scheduled to leave for Singapore on June 2, with plans to transit to Hong Kong.
After boarding the plane, the victim placed her bag containing valuables in the compartment above her seat.
Before takeoff, Liu reached into the compartment and stole two debit cards and S$169 (US$125) in cash from the victim's bag, Channel News Asia reported. He then placed the stolen items into a drawstring bag and handed it to his accomplice.
Two fellow passengers witnessed Liu's actions.
A flight attendant also observed him passing the bag to another man and instructed Liu to return to his seat.
After the flight landed, the two witnesses saw the victim retrieve her bag from the overhead compartment and realized it did not belong to Liu.
They approached the victim and advised her to check her belongings. Upon discovering that her cards and cash were missing, she reported the theft to police.
Authorities later traced and arrested Liu and his accomplice at Changi Airport.
Wang's case is still before the courts.