The amendment is to Planned Development No. 1426, which authorises zoning for the building of Bally's Chicago Casino, a $1.7bn "flagship entertainment destination."
Bally's says the first phase of the project will include a one-million-square-foot casino building, a 500-room hotel and a 3,000-person.
The battle for a Chicago licence took some time but Bally's was considered a favourite from early in the process.
The Council's support follows the Plan Commission and Committee on Zoning recommended approval of the project earlier this week.
Bally's Chairman Soo Kim said: "This is a significant achievement and another critical step forward in the process of developing Bally's Chicago.
"We are confident the casino will bring numerous long-term, positive economic benefits, including good-paying, union jobs, to this great city."
There has been plenty of Bally's news elsewhere this week, first with the company appointing a new EVP and Chief Legal Officer in Kim Barker Lee.
Company CEO Lee Fenton added: “We are excited to welcome Kim to Bally’s and are confident that she will make an excellent addition to our global leadership team."
Meanwhile, Bally's also entered into a labour neutrality agreement with the International Union of Operating Engineers (IUOE).
Per the agreement, the parties will take a neutral approach to organise campaigns that will enable every Tropicana Las Vegas employee to make an informed decision regarding their union representation.