The attention to the cold island effect of urban blue and green spaces has grown because of reducing urban heat island effects. The global urbanization process has rapidly accelerated. In recent decades, especially in developing countries, the urban heat island effect (UHI) has affected human life and health. An increase in urbanization occurred between 2002 and 2014. In Lucknow City, India, the average temperature increased by more than 1 °C, from 36.7 °C to 37.8 °C. The study explores the impact of urban blue and green spaces on the thermal environment, focusing on their potential for heat mitigation and emission reduction through a literature review. Blue and green spaces play a crucial role in reducing the temperatures associated with UHI through several mechanisms, including shading, evapotranspiration, and altering the thermal properties of surfaces, which can lower UHI by up to 4 °C. Green infrastructure is crucial in addressing climate change by providing microclimatic controls in urban areas, acting as an ecosystem manager and natural resource sink, and providing spaces to adapt to extreme climate variations. These results contribute to urban green and blue spaces (UGBS) design and urban planning to minimize the potential impact of UHI on the environment. An increase of 25% in vegetative cover lowered summertime afternoon temperatures in the Sacramento metropolitan area by 0.5–3 °C. Blue-green infrastructure is a sustainable solution for urban areas to combat climate change. Offering socioeconomic benefits, aesthetic and ecological benefits, and enhancing infrastructure efficiency, collaboration, and overall city benefits help to improve urban comfort and promote sustainable urban development.