President Uhuru Kenyatta, Attorney General Githu Muigai and Thirdway Alliance's Dr Ekuru Aukot have been enjoined in the case in which businessman Harun Mwau is seeking to stop the electoral agency from conducting repeat polls without nominations.
High Court judge Enoch Chacha Mwita issued the directive after lawyers representing the three told court there was need for them to be enjoined in the case.
They claimed that the matter is of great public interest and both Mr Kenyatta and Dr Aukot are presidential candidates.
According to the AG, he intends to defend public interest in the matter.
"Mr Kenyatta, Dr Aukot and the AG are hereby enjoined as interested parties and they should therefore file as well as serve the case documents by October 19, indicating the time," said Justice Mwita.
On Monday, Mr Mwau, the former Kilome MP, sued the Independent Electoral and Boundaries Commission (IEBC) and its Chairman Wafula Chebukati.
Through lawyer Benjamin Musyoki, Mr Mwau faulted the IEBC for publishing a gazette notice on September 5 regarding the October 26 repeat presidential polls contrary to the law.
According to him, the Supreme Court directed the IEBC to hold fresh polls, which he argues must entail nominations as per the Elections Act.
Mr Mwau says that while nullifying the August 8 presidential election, the top court directed the IEBC to hold fresh elections in conformity with the Constitution and Elections Act.
He wants the High Court to determine whether fresh or new elections can be held without nominations or whether polls can be held based on a nomination that has been nullified.
The case will be heard on October 23.