Urban waterfront space is a significant type of public open space that offers individuals a range of cultural ecosystem services (CESs). However, identifying the CES of such space through social media data has become a challenge in the digital age. The study used 22 urban waterfront spaces in the core section of the Huangpu River in Shanghai, China, as an example to identify CES types by constructing a lexicon and to analyze perceptions by applying the importance-performance approach. The results revealed that: (1) Fitness and recreation were found to have the highest perceived word frequency among CES types, while education had the lowest frequency. According to the word frequency proportion of cultural service, waterfront spaces can be classified into three dominant types: art and inspiration-oriented, heritage and sense of place-oriented, and comprehensive-oriented. (2) Overall satisfaction was 93.47%, with higher levels of satisfaction for all types of CES, with the highest level of satisfaction at 97.90% for aesthetics. (3) The future improvement of waterfront spaces need to focus on recreation, social relation, fitness, art and inspiration services. This study can capture the public’s perception of waterfront spaces and afford decision-makers more precise recommendations for design.