Around 20 ministers are likely to take oath at the ceremony, and almost half of them are expected to be those from Sena.
The ceremony will be held at Vidhan Bhawan premises at 10 AM.
Fadnavis had met BJP president Amit Shah in New Delhi yesterday and is believed to have got the nod for BJP probables in the expansion exercise.
Among those in reckoning from BJP include senior legislators Girish Bapat (Pune) and Girish Mahajan (Jalgaon) and also Babanrao Lonikar and Sambhaji Patil Nilangekar, both from Marathwada.
From Mumbai, there is speculation over inclusion of Mangal Prabhat Lodha, the Malabar Hill MLA, and Raj Purohit, who represents Colaba, and Ashish Shelar, the Bandra MLA, who is also city BJP chief.
Presently, there are eight cabinet rank and two ministers of state in the ministry.