Joasaph of Belgorod, in the world Ioakim Andreevich Gorlenko, was born on September 8, 1705, in Pryluky, Kyiv province, to Colonel Andrei Dmitrievich Gorlenko of the Pryluky Cossack regiment. His mother, Maria Danilovna, was the daughter of Hetman D. P. Apostol. Among his relatives were church figures, including his uncle, Hieromonk Pakhomiy, and his brother, Archimandrite Mitrofan.

In 1709, his father and grandfather, supporting Mazepa, fled to the Ottoman Empire but later returned. In 1713, Ioakim entered the Kyiv-Mohyla Academy under the patronage of his uncle Pakhomiy. At the age of 11, he decided to become a monk but hesitated to inform his parents. In 1723, upon returning home, he asked for a blessing for monastic tonsure but was refused. Despite this, he secretly entered the Kyiv-Mezhyhirskyi Monastery and on October 27, 1725, took the rassaphore with the name Hilarion. In 1727, he was transferred to the Kyiv-Brothers Monastery, where he took monastic vows with the name Joasaph and was ordained as hierodeacon.

After graduating from the academy, Joasaph became a teacher, and in 1733, he was appointed ecclesiarch of the Kyiv-Brothers Monastery. In 1734, he was ordained as hieromonk and transferred to St. Sophia Cathedral. In 1737, he was appointed abbot of the Lubny Mhar Monastery, which he significantly improved.

In 1744, Joasaph was elevated to the rank of archimandrite and summoned to Moscow. In 1748, he became the Bishop of Belgorod and Oboyan. Despite his poor health, he frequently visited his diocese. During one of these visits, he fell ill and passed away on December 10, 1754, in the settlement of Grayvoron.

After his death, Joasaph's body remained incorrupt in the Holy Trinity Cathedral until the end of February 1755 due to a delay by Bishop Ioann Kozlovich, who was appointed for the burial. Only on February 28, 1755, was he buried in the cathedral's crypt. At the initiative of his brother, a chapel was consecrated above the crypt. In 1911, Joasaph was canonized by the Russian Orthodox Church and is venerated as a saint. Since the 2000s, he has also been honored among the Assemblies of the Radonezh and Kursk saints.