Cold ironing is a remarkable electrification innovation in the maritime industry for ship transportation, in which diesel engines driving ship generators for onboard load are switched to shore-supplied electricity during berthing. This facility serves not only as an alternative power supply for electric ships but also as part of the green port's strategy. Cold ironing installation is expected to be unavoidable in the long term for all port operators due to stringent emission policies. Even though cold ironing is used by a few ports across the world, it is still regarded as an underutilized technology due to the high upfront cost associated with the shoreside installation and ship's retrofitting, as well as unclear benefits for both sides. The involvement of diverse types of ships with different power requirements, various operational schemes, unpredictable berthing hours, uncertainty in the availability of local power sources, and synchronization issues among others make it very complex to coordinate for optimal cold ironing operations, which necessitate further investigations. This review gives an overview of cold ironing technology, including its operation, power requirement, standardization, challenges, and important assessment for evaluation. A cold ironing implementation strategy to achieve the ultimate seaport decarbonization goal through a synergy between cold ironing and seaport microgrid is also addressed.