The High-Luminosity Large Hadron Collider (HL-LHC) aims to increase the LHC data-set by an order of magnitude in order to increase its potential for discoveries. The high pileup at the HL-LHC presents a highly challenging environment to particle detectors. To cope with this, the current Inner Detector of the ATLAS experiment will be replaced with a new all-silicon Inner Tracker (ITk). The expected tracking performance of the ITk is presented and impact of the tracking performance on vertex reconstruction, jet flavour tagging and pileup jet rejection is shown. These studies were performed for two possible options of the pixel sensor pitch.