Mangroves are woody plants that can thrive in coastal saline or brackish water between land and sea, and they constitute a major portion of coastal wetlands. The mangrove ecosystem harbours growth of wide variety of epifaunal communities such as macroalgae, bacteria, fungi and invertebrates. The salt tolerance of mangroves makes them attracted to these species. Also, mangrove forests are one of the most productive ecosystems in the world which play a significant role in global carbon cycle. The macroalgae and mangroves together play a vital role in sustainability of marine ecosystem in many ways. Most of the algae are lithophilic in nature and grow abundantly on rocky substrata in the marine habitat. In estuary deltas, mangroves act as a substratum for their growth and development. The holdfast of mangroves, which is analogous to roots of higher plants, supports algae to attach on mangroves and grow abundantly. The diversity and distribution of mangroves associated with marine algae from mangroves of India have been discussed in this chapter. According to the previous reports, Sundarbans mangrove forest ranks highest in the number of algal communities both in terms of microalgae and macroalgae.