Everyone Active will take over the English Institute of Sport, Ponds Forge International Sports Centre and IceSheffield from January 2025.
It will also manage Hillsborough, Concord and Springs, as well as Heeley swimming pool and three golf courses.
From 2026, the operator is expected to take control of Graves, Thorncliffe and Wisewood leisure centres, which have been operated by Places Leisure since 2016.
Everyone Active said it aimed to tailor the different facilities and services to cater for the communities they served.
Sheffield City Council also confirmed earlier this month that as part of its planned £117m investment plan, Sheffield Arena and the City Hall were also set be upgraded.
It had earlier announced that ASM Global would be the new operator for those venues.
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