Trostianets or Trostyanets (Ukrainian: Тростянець, pronounced [trosʲtʲɐˈnɛtsʲ]; Russian: Тростянец) is a city in Okhtyrka Raion of Sumy Oblast of northeastern Ukraine.

Landmarks include a neo-Gothic "round courtyard" (1749), the late Baroque church of the Annunciation (1744–50), the 18th-century Galitzine palace, and a "grotto of nymphs" (an 1809 centenary memorial to the Battle of Poltava).

The city suffered major damage to its infrastructure during the fighting and a Ukrainian official said that the retreating Russian troops had mined a local hospital.

[12] During the fighting and shelling, the Krasnotrostyanets forest experimental station, located in the house of the manager of the estates of Leopold Koenig, was destroyed (an architectural monument of national importance).

As a result of the fire, the chocolate factory "Ukraine" "Mondelēz International" (formerly "Kraft Foods") was partially destroyed.

[15][16][14] On March 2, 2024, a HESA Shahed 136 drone was shot down over Trostianets, and residential buildings were damaged as a result of falling debris.

There are several architectural monuments in the city - the "Round Yard" of 1749, the Golitsyn's manor house, churches, the nymphs' grotto of 1809 and others, which are gradually being repaired and restored.

This enterprise belongs to the company "Mondelēz International" (formerly "Kraft Foods"), which is known for its trademarks "Crown", "Alpen Gold", "Jacobs", "Tuc", "Barny" and Milka.

Trostianets is a football club based in the city, which made its debut in the Ukrainian Second League in the 2021–22 season.