A total of 10 people - all arrested on Monday - now face preliminary charges ranging from armed robbery to kidnapping and handling stolen goods.
Those brought before an investigating judge on Friday include the alleged "mastermind", reports say.
Kardashian West was held at gunpoint and tied up by robbers while staying at an exclusive flat in Paris in October.
The TV reality star was attacked while her bodyguard looked after her sister at a nightclub. The gang stole €9m (£8m; $9.5m) of jewellery, including a diamond ring valued at about €4m.
Four people were placed under investigation on Thursday, including a man - named as Yunice A, 63 - accused of robbing Kardashian at gunpoint and leaving her bound and gagged.
The suspects brought before a judge on Friday include a 60-year-old believed to be the mastermind of the plot, French media report.
Police have been investigating whether the gang was tipped off that the star's bodyguard was not at the residence at the time of the robbery.
Although there has been no trace yet of Kardashian West's missing jewellery, police did recover an estimated €300,000 worth of items during raids on Monday.
French officials have placed six new suspects under formal investigation over the Kim Kardashian West robbery.