Security footage showed the two women, 25-year-old Indonesian Siti Aisyah, and 29-year-old Vietnamese citizen Doan Thi Huong, walking up behind Kim and rubbing their hands on his face.
Malaysian authorities claim the pair were trained by North Korean agents to swab Kim's face with the nerve agent.
North Korea has repeatedly and vehemently denied any involvement in the assassination of Kim.
But representatives of Doan and Aisyah said the two women were duped into thinking that they were participating in a prank TV show.
The two women arrived at court Monday wearing bullet proof vests with their eyes downcast, surrounded by a heavy police presence.
Both woman are charged with murder under section 302 of the Malaysian criminal code, which carries a mandatory death sentence.
Defense lawyer Hisyam Abdullah, who represents Doan, told CNN the lawyer who was appointed by North Korea to watch the brief has been instructed by their embassy to disengage himself from observing proceedings.
A second lawyer for the Vietnamese woman, Hisyam Teh Poh Teik, told CNN he expects the prosecution case to last until November, while the defense will start in the new year.
"Doan looks forward to the trial where her innocence will be established," said Teh.
'She was ... used by someone'
According to Malaysian authorities, Kim was at the airport on his way back to see his family in Macau when his face was swabbed with the deadly nerve agent.
Kim immediately sought help at a service counter, but while waiting at the airport clinic he fainted. Although an ambulance was called, Kim died on his way to the hospital.
Tests on his face and eyes postmortem revealed the presence of the deadly nerve agent.
"She will be proven innocent," he said. "She wouldn't harm anyone, not a child, let alone someone so powerful like that."
Son of a dynasty
Kim Jong Nam was the eldest son of former North Korean leader Kim Jong Il, who ruled the country from 1994 until his death in 2011.
Kim Jong Il, in turn, was succeeded by his youngest son, and Jong Nam's half brother, Kim Jong Un.
The eldest of the Kim siblings, Kim Jong Nam was born to a famous married actress and kept in hiding in case his existence hampered his father's chances of taking over from the country's founder, his grandfather Kim Il Sung.
Educated around the world, Kim Jong Nam worked for the North Korean government for a while and was long considered to be his father's favorite child, according to analysts.
But after he was embarrassingly caught at Tokyo airport with a fake passport in 2001, allegedly on his way to Disneyland, he rapidly fell from grace.
He moved to Macau in the mid-2000s, where he maintained a lavish but subdued lifestyle, fearful of a younger brother who analysts say would always see him as a threat.
CNN's Kocha Olarn, Salhan Ahmad and Josh Berlinger contributed to this report.