The LHC Injectors Upgrade (LIU) project has been executed to increase the intensity and brightness in the LHC injectors and match the challenging requirements of the High-Luminosity LHC (HL-LHC) project, while ensuring high availability and reliable operation of the whole complex up to the end of the HL-LHC era. Fulfilling this goal has required extensive hardware modifications and new beam dynamics solutions across the entire LHC proton and ion injection chains. The great majority of the LIU hardware modifications were implemented during the 2019-2020 CERN accelerators shutdown. Currently, the upgraded injectors are being recommissioned with beam, following a detailed milestone plan for beam parameter ramp-up over the next three years. Close follow-up and a careful preparation of mitigation actions will be the key to ensure the ultimate performance reach.