Plastic pollution is a significant issue when managing aquatic environments. We determined the prevalence, abundance and type of plastic, and drivers of accumulation, on shorelines in the Swan Canning Estuary in Perth, Western Australia. We collected seasonal samples of plastic from 39 shorelines for 12 months. Sites facing north, south, east and west were selected to determine the influence of wind on plastic debris accumulation. Comprehensive site morphology data was also collected. We found plastic on every shoreline sampled, and accumulation was greatest during winter and spring and on sites facing south and west, the direction of the prevailing wind. Greater bank height and vegetation cover were also linked to higher plastic accumulation and while the vegetated section of the bank had the greatest quantity of plastic debris, this effect was largely restricted to banks facing south or west. Expanded polystyrene fragments and fragmented hard and soft plastics were the most prevalent plastic items. This study has provided a comprehensive baseline and insight into factors driving plastic accumulation onto shorelines on urban estuaries at both fine and coarse spatial scales and provides a significant resource to management agencies.