Bulancak is a district of Giresun Province on the Black Sea coast of Turkey, near the city of Giresun. Its former name is Terastios. It neighbours the district of Piraziz which used to be a part of Bulancak, Altinordu district and Kabadüz districts of Ordu in the west, Giresun City in the east and the district of Dereli in the south.

The municipality was established in 1887 and became a district in 1934. According to the census conducted in 2020, the total population of the district is 68,557. 47,366 of this population live in the urban area of the district. With a population of 68,557 Bulancak is the largest district in the province apart from Giresun City itself and is one of the largest districts on the Turkish Black Sea coast. Because of its closeness to Giresun City, it is easily reachable by public transport and thus Bulancak can be considered a part of Giresun City's metropolitan area. Bulancak's general economy is based on fishing and agriculture. The main agricultural product in the district is hazelnuts, and is traditionally the main means of income for the people of the region.

The known history of the region goes back to the Hittites. While the region was under the rule of the Hittites in 1400-1200 BC, the Trabzon-Erzurum-Giresun regions were called "the land of the Azzi". The Milesians who were traders along the Aegean Region in antiquity established their trading colony of Kerasous, which the city and province of Giresun gets its name from, approximately around the modern town of Bulancak.