Oleg Ivanovich Ryazansky was born in 1350. During the period of the "great turmoil" in the Golden Horde, before power concentrated with Mamai, Oleg, along with Vladimir Pronsky and Titus Kozelsky, achieved victory over the Horde prince Tagai at Shishevsky Forest in 1365.

From 1370 to 1387, Oleg actively tried to preserve the independence of his principality, located on the border with the steppe and vulnerable to Horde raids. In 1370, he became one of the organizers of the gathering of troops to assist besieged Moscow by Olgerd, but in 1371, he was defeated by the troops of Dmitry of Moscow under the command of Prince Dmitry Bobrok-Volynsky in the Battle of Skornishchevo. The Ryazan principality was occupied by Vladimir Pronsky, but by 1373, Oleg regained power with the help of the Tatar murza Solokhmira. In 1377, Ryazan was devastated by the Horde prince Arapsha, and Oleg barely escaped capture. In 1378, Dmitry led his troops beyond the Oka and, uniting with Danila Pronsky, achieved victory over the Horde army in the Battle on the Vozha. In 1379, Ryazan was again ravaged by Mamai.

In 1380, Oleg entered into negotiations with Mamai and Jagailo against Dmitry, which is often seen as a betrayal of the common Russian cause. However, some historians consider this a diplomatic game aimed at protecting his lands from devastation and misleading Mamai and Jagailo. Dmitry moved his troops beyond the Oka, not attacking Ryazan, but passing west of its lands. The "Zadonshchina" mentions the death of 70 Ryazan boyars on the side of the Russians. Some Ryazans, in the absence of their prince, plundered the convoys returning from the Kulikovo Field through Ryazan land. In 1381, Oleg recognized himself as a "younger brother" and concluded an anti-Horde treaty with Dmitry, committing to return prisoners captured after the Battle of Kulikovo.

In 1382, Tokhtamysh suddenly attacked Rus. Dmitry did not have time to gather forces, and Oleg, to save his lands, showed the Horde the fords on the Oka. However, they still plundered Ryazan on their way back. In the autumn of that year, Dmitry also conducted a punitive campaign against Ryazan. In 1385, taking advantage of Moscow's weakening after Tokhtamysh's invasion, Oleg captured Kolomna and defeated the Moscow army near Perevitsk. Through the mediation of Sergius of Radonezh, a perpetual peace was concluded with Dmitry Donskoy, and in 1387, Oleg married his son Fyodor to Dmitry's daughter Sophia.

In the following years, Oleg supported his son-in-law, the Smolensk prince Yuri Svyatoslavich, against the Lithuanian Vitovt, who sought to capture Smolensk. Clashes occurred on Lithuanian and Ryazan territory. Oleg managed to temporarily restore the throne to Yuri Svyatoslavich. However, in 1402, the Ryazan principality suffered defeat in the Battle of Lyubutsk, and his son Rodoslav Olgovich was captured, which weakened Oleg's forces.

Before his death, Oleg took monastic vows and the schema under the name Joakim in the Solotchinsky Monastery, which he founded 18 versts from Ryazan. His wife, Princess Euphrosinia, also ended her life as a nun.

Prince Oleg left a controversial legacy and a posthumous bad reputation created by Moscow chroniclers. He was called "the second Svyatopolk," but the Ryazans loved him and remained loyal both in victories and after defeats. Oleg was a significant figure in the life of Rus in the 14th century. In the pre-final charter between Dmitry Donskoy and Mikhail of Tver, the main competitors for the Grand Duchy of Vladimir, Oleg acted as an arbitrator, which attests to his authority.

Grand Prince Oleg Ivanovich Ryazansky died on July 5, 1402, and was buried in the Intercession Church of the Solotchinsky Monastery. He is venerated by Orthodox Christians as a righteous local saint. His wife Euphrosinia died on December 5, 1404, or 1406, and is also venerated as a local saint. In 1955, by the decree of the Holy Synod, the remains of Oleg and Euphrosinia were transferred to the Church of the Nativity of the Most Holy Theotokos of the Solotchinsky Monastery. After the monastery was closed, their remains were handed over to the Ryazan Provincial Museum, and then to the St. John the Theologian Monastery, after which they were returned to the Solotchinsky Monastery. Subsequently, the spouses were reburied in the Nativity of the Theotokos Cathedral of the Ryazan Kremlin.