"We have signed him and hopefully he will be available after four games," said Victorians officials on Tuesday.
The Australian will arrive after the departure of Pakistani Shoaib Malik, who is expected to be available for the opening four matches, as he will join the Pakistan team ahead of the series against New Zealand.
Smith and Warner will be serving the ban till March 29, 2019 while Bancroft's time away is until December 29 this year.
Smith compatriot Warner joined Sylhet Sixers for the upcoming edition of BPL.
Comilla Victorians: Tamim Iqbal, Imrul Kayes, Steve Smith, Mohammad Saifuddin, Shoaib Malik, Asela Gunaratne, Liam Dawson, Amin Yamin, Evin Lewis, Waqar Salamkheil, Shamsur Rahman, Sanjit Saha, Mosharraf Hossain, Mohammad Shahid, Shahid Afridi, Thisara Perera, Abu Haider Rony, Anamul Haque, Mehedi Hasan and Ziaur Rahman