In recent years, green infrastructure has been extensively used as a strategy to mitigate adverse environmental effects due to rapid urbanization. Vegetated spaces play an important role in moderating and improving urban environments for more comfortable and healthier living conditions. This study investigates integration of green infrastructure, specifically green roofs and rain gardens, into urban planning to enhance environmental sustainability. A case study approach is used to examine implementation of green infrastructure elements in three cities, such as New York City (USA), Copenhagen (Denmark), and Singapore. The findings reveal common challenges faced by these cities such as high installation and maintenance costs, technical and structural concerns, policy and regulatory barriers, and lack of public awareness to integrate green infrastructure. Successful strategies for overcoming these challenges include strong policy support, public-private partnerships, integrated planning, awareness programs, and providing technical training for professionals. Future research which includes expanding sample size and diversity, exploring government and industry support, and assessing social equity impacts are recommended.

Keywords: Green Infrastructure, Green Roofs, Rain Gardens, Stormwater Management, Urban Heat Island, Biodiversity, Energy Savings, Public-Private Partnerships