The Cabinet approval, which will see the city’s population rise from around 125,000 to just under 210,000, will bring to an end a dispute over the boundary change.
Local Government Minister Eoghan Murphy will ask his Cabinet colleagues to approve the bill for the extension, which will account for around 70% of the population of Metropolitan Cork.
The actual Local Government Bill is expected to be published later this month.
Changes will bring Ballincollig, Blarney, Tower, Cork Airport, and Glanmire, into the city.
The legislation will give effect to the compromise which emerged on December 6, after talks between representatives of Cork city and county councils overseen by the Implementation Oversight Group (IOG), in a bid to break the deadlock over a larger extension proposed in the Mackinnon report.
When the group issued its report to Mr Murphy, he urged both councils to agree on the boundary line, which would allow him use a ministerial order to give effect to the extension.
A compromise emerged in December after weeks of negotiation between the city and county councils. Nonetheless, concerns remain about the move among residents in areas of the county. It is thought the deal allows for a review in 12 to 15 years.
One concern centres on rates and losses in revenue for the county. It is thought the Cork County will retain the commercial rates-rich industrial area of Little Island as well as Carrigtwohill.
Mr Murphy will also seek approval today for the integration of Galway City and County Councils. An expert group earlier this year unanimously recommended the establishment of a unified Galway authority rather than boundary changes or retaining of the status quo.
A separate decision on changes to electoral areas in counties is not expected to go to Cabinet until next week.
There have been calls for Cork City to get more councillor positions, given it is the first boundary change since 1965. This is especially so given that the city’s population is set to increase by up to 100,000 and that Cork City Council would retain only 31 seats.
This review of boundary changes is being separately conducted by John Paul Phelan, minister of state for Local Government and Electoral Reform.