Seville, Spain's fourth largest city and the capital of Andalusia, is one of the most visited cities in the country and increasingly in Europe. Tourism has traditionally been an important sector for the urban economy, but after the 2008 financial crash it has become the city's main source of income. Tourist numbers have soared over the last decade and they are likely to keep growing now that the Lonely Planet has labelled Seville the best city to visit in 2018 and Airbnb has chosen Andalusia as one of the top destinations for 2019. There has also been an increase in the number of migrants from wealthy countries over the last few years. Not surprisingly, these migrants and tourists share spatial patterns: both generally concentrate on Seville's historic district and urban centre. We argue that the rapid increase of tourism and the settlement of lifestyle migrants in this part of the city have triggered spatial processes that have resulted in social injustice. Therefore, we explore whether the growth of visitor numbers has reached the extent of overtourism, because the tourist infrastructure and its activities may clash with those of local residents. We also study whether the socio-economic profile of many of these residents has changed due to migration, which could potentially mean the beginning of a transnational gentrification process. Seville's city centre is becoming a privileged place, where the average Sevillian cannot afford to live and increasingly feels out of place. Our argument is supported by a combination of quantitative data analysis (demographic, housing and tourism statistics) and qualitative research (interviews) analyses. Our case illustrates how tourism helps to reshape historic urban districts and becomes socially unsustainable, as it gradually excludes local communities. [ABSTRACT FROM AUTHOR]