Sky Sports reported that Carneiro, who left the club earlier this season following her demotion from match day duties, will seek damages from Mourinho for sexual discrimination.
She is also said to be claiming for reinstatement to her role at the club.
Press Association Sport reported last month that legal papers were served on Mourinho as part of the claims against him and against the club.
It means the Portuguese manager will have to appear in person at an employment tribunal unless the case is settled out of court beforehand. Under employment law, an individual can be personally liable for damages if victimisation or discrimination can be proved.
The claim against Mourinho is reportedly on the basis that he was instrumental in the actions against Carneiro in having her dropped from first-team duties and effectively demoted. The Employment Tribunal central office has been formally notified of both the claims, and Mourinho and Chelsea had 28 days to respond once legal papers have been received.
The latest development will heap even more pressure on the 52-year-old who has seen his side lose six out of 11 matches in the Premier League so far to leave the reigning champions in 15th spot in the table. He was given a one-match stadium ban and £40,000 fine by the Football Association on Monday after admitting a misconduct charge for his behaviour towards match officials at half-time during Chelsea's defeat by West Ham last month.
Carneiro's case against Mourinho personally would continue even if he were to leave Chelsea.
Image credit: Reuters
The controversy over Carneiro goes back to August 8, the opening day of the season, when Mourinho criticised her and head physio Jon Fearn for going on to the pitch to treat Eden Hazard after being called on by referee Michael Oliver. The action meant that Chelsea were temporarily down to nine men against Swansea, and afterwards Mourinho called Carneiro and Fearn "impulsive and naive".
Carneiro did not appear on the bench again for first-team duties and is now seeking a claim for constructive dismissal after parting company with the club.
Mourinho was cleared of using discriminatory language towards her following an investigation by the FA, which caused further controversy after Carneiro revealed she had not been spoken to personally during the investigation, nor asked to provide any statement.