Tropical-extratropical cloud bands are elongated cloud structures bridging tropical and midlatitude regions, and are crucial drivers of precipitation. While these cloud bands result from tropical-extratropical interactions, the specific role of midlatitude dynamics for their formation, evolution, and variability remains unclear. In this study, we use an object-based approach applied to reanalysis data to investigate how stratospheric potential vorticity (PV) intrusions, as indicators of Rossby wave breaking, influence cloud band formation and orientation in the South Pacific region. Our findings reveal that PV intrusions are strongly linked to cloud bands, with cyclonic PV anomalies steering tropical moisture poleward and shaping the diagonal orientation and spatial extent of the cloud bands. Additionally, we show that the variability of cloud bands closely follows the variability of PV intrusions, with ENSO modulating their occurrence and spatial distribution. These findings highlight the central role of Rossby waves in shaping tropical-extratropical cloud bands.