Urban Green Spaces (UGS) play a fundamental role in improving the quality of life in urban environments, especially as metropolitan areas experience population growth and increased density. The COVID-19 pandemic has highlighted the importance of these spaces, which have become useful means for improving physical and mental well-being after lockdown periods. Moreover, tourists increasingly value green spaces in their vacation destinations, and ecotourism has become a prominent trend in the post-pandemic era. Therefore, this work aims to predict tourists’ overall sentiments toward Retiro Park, a renowned UGS in Spain and a UNESCO World Heritage Site, based on the number of online reviews (e.g., one-star, two-star, three-star reviews, etc.). This work uses sentiment analysis techniques and the multilayer perceptron neural network. Seven hundred seventy online reviews of Retiro Park, sourced from TripAdvisor and Civitatis, were collected to evaluate the effectiveness of this approach. The results indicate that this approach can offer UGS managers a valuable tool for monitoring public satisfaction. This information can serve as a foundation for implementing strategies to improve tourist satisfaction, promote a more sustainable city image, and support the growth of ecotourism.