On Saturday, Line 1 will be closed between Bloor-Yonge and Osgoode stations while the TTC works to install its automatic train control system.
The TTC said all stations will remain open for fare sales as well as access to surface routes and Line 2.
On Sunday, there will be no service from Sheppard-Yonge and St Clair stations due to track work.
All stations will remain open for fare sales and access to surface routes and Line 4.
However, at York Mills Station, the Old York Mills Road entrance will be closed. The TTC advised customers to use the other station entrances located in the York Mills Centre, Yonge Corporate Centre, and at the corner of Yonge Street and Wilson Avenue.
At Lawrence Station, the automated entrances at Ranleigh Avenue and Bedford Park Avenue will also be closed. Customers are advised to use the entrances at Yonge Street and Lawrence Avenue.
Shuttle buses will operate on both days, the TTC said. Customers requiring Wheel-Trans should speak with a TTC customer service employee to request the service.