Ashok Prasad, an escort agent, is the "mastermind" of the robbery incident which took place outside a five-star hotel in western suburb of Vakola on Sunday night, police said.
"The accused is a resident of Mira Road and was arrested from there," said M Vavhale, Senior Inspector of Vakola Police Station.
However, the woman and her driver, who is also wanted in the case, are absconding and a search is on to trace them, he said.
The victim, a businessman, visited the city on Sunday and allegedly asked for a female escort from an agency through Prasad, an agent, said Vavhale.
The MP's son was threatened on knife-point by the woman and her driver, who looted valuables worth around Rs 1.5 lakh from the victim and fled, police said.
Prasad was produced before a local court, which remanded him in police custody till August 24, they added.