Carneiro's action is believed to centre on the allegation that the manager was "instrumental" in having her dropped from first team duties and effectively demoted.
Mourinho will be served with legal papers this week and if the case proceeds he could be required to appear at an employment tribunal.
The move comes as part of separate but connected claims against Mourinho and the club, which will be heard in court unless the case is settled beforehand.
Under employment law, an individual can be personally liable for damages if victimisation or discrimination can be proved.
After the game Mourinho said she had been naive, and she was subsequently removed from the bench.
The FA ruled Mourinho should not face charges for using discriminatory language.
But Carneiro complained that she had not been given a chance to give evidence.
The legal action heaps pressure on Mourinho, 52, who has seen his side lose six out of 11 Premier League matches so far this season.
The doctor's lawyers said neither she nor they could comment as the case is sub judice. Chelsea did not respond when asked if they wished to comment.
Source: Bloom Sports and Sky Sports
