Sumy was founded by the Cossack Herasym Kondratyev from Stavyshche, Bila Tserkva Regiment on the banks of the Psel River, a tributary of the Dnieper.

[5] In the 1670s, Sumy was expanded with the addition of a fortified posad (craftsman town), after which it became the biggest fortress in Sloboda Ukraine.

[5] At the end of the 17th century, Sumy played a role as a collection point for Muscovite troops during the Crimean campaigns of 1687 and 1689.

[5] Established under the leadership of Prince A. Shakhovskoy, the Commission on streamlining the Sloboda Cossack regiments was located in 1734–43 in Sumy.

[5] From its establishment and until the liquidation of Cossackdom in Sloboda Ukraine in 1765, the Cossack officer family of Kondratyevs exercised great influence over the city.

[5] After a period of stagnation (1765–1860s), Sumy began to transform into a big industrial and trade center with Paul's Sugar-Refining Factory (est.

[5] With the construction of a railroad Vorozhba – Merefa, the Sumy train station was built in the city in January 1877.

[6] During the German occupation of Ukraine during World War II (1941–1944), Sumy sustained heavy damage and was occupied from 10 October 1941 to 2 September 1943.

In May-June that year, the Germans and their Hungarian allies killed an additional several dozen Jews, along with thirty Roma.

Sumy's climate is a warm-summer humid continental (Köppen: Dfb)[13] with cold and snowy winters, and hot summers.

The Blessed Virgin Mary Annunciation Church was established in the city in 1901 and consecrated in 1911, but closed by governmental authorities two decades later; the churchhouse was thereafter used for non-religious purposes (e.g., it was used as a gym for Oleksandrivska Gymnasia) until its restoration as a Roman Catholic parish in May 1994, after the disintegration of the Soviet Union.

Paintings of Taras Shevchenko, Vladimir Borovikovsky, I. Shyskin, Arkhip Kuindzhi and Tetyana Yablonska are on display, including a Dutch landscape by a painter of Jan van Goyen's circle.

“Abbacia and the Adriatic Sea are wonderful, but Luka and Psiol are better” – he wrote in his letter from Italy to his friends in Sumy in 1894.

The field hockey club MSC Sumchanka has won the Ukrainian championship 12 times and was the European champion once.

The Ukrainian Premier League football club FC Kharkiv were leasing the city's state-of-the-art Yuvileiny Stadium.

The Yuvileiny Stadium, formerly known as Spartak, was planned to be renovated just before dissolution of the Soviet Union and in 1989 was demolished to be built anew.