Metropolitan Sofronius was born on 20 March 1888 in the Odrin village of Novo Selo, the Ottoman Empire, with the secular name Stoyko Nedyalkov Chavdarov. He went to primary school in his native village in Dedeagach and graduated the Bulgarian High school „Dr. Peter Beron“ in the city of Edirne. In the period 1905 – 1911 he studied in the Constantinople spiritual seminary.
On 18th September 1911 he was tonsured a monk under the name of Sofronius in the Cathedral of St. Stephen in Constantinople and was ordained a hierodeacon by the Metropolitan bishop Meleti Veleshki. Then he served as a deacon at exarch Joseph I. of Bulgaria and as a scribe at the Bulgarian Exarchate.
In 1912 he joined the Spiritual Academy in Kiev, where he followed until 1915. After the liberation of Vardar Macedonia during the First World War from 1 April 1916 till 23 September 1918, he was secretary of the Veles Metropolis. After the War from 1 September 1919 till 1 September 1922 he was an exarchist deacon and preacher in Constantinople and a teacher at the Bulgarian high school in Pera. On 24 April 1921 St. Stephen was ordained as a hieromonk by Metropolitan Meleti Veleshki.
In 1922 he graduated from the Theological University of Chernivtsi University. From 1 September 1922 to June 1924 he attended a theological specialization at the Institute of Canonical Law at the University of Strasbourg, France. From 1 October 1924 to 1 September 1929 he was a protosingel of the Sofia Metropolis. On 19 October 1924 according to a decision of the Holy Synod he was brought into Archimandrite dignity by the Metropolitan Stefan Sofiiski. From 1 September 1929 until the end of October 1931 Archimandrite Sofronius was the head of the Cultural and Educational Department at the Holy Synod.
On 1 November 1931 he was ordained a bishop with the title „Znepolski“ and was appointed a vicar of the Sofia Metropolitan Stephen. Due to the deteriorated state of health of Metropolitan Philip Tarnovsky on 26 March 1934 he was appointed as his vicar and ruler of the Tarnovo diocese. From 1 July 1935, the vicar of Bishop Stefan Sofiyski was re-vicar.
On 22 September 1935 Bishop Sofronius Znepolski was elected and on 6th October he was canonically established for Tarnovo Metropolitan.
After the defeat of Yugoslavia from Germany in the spring of 1941 the Bulgarian Exarchate restored its diocese in the parts annexed by Bulgaria from Vardar and Aegean Macedonia and in Western Thrace. The temporary administration of the Skopsko-Veles Diocese was handed to Metropolitan Sofroniy Tarnovski with assistant bishop Maxim Branicky. As a Diocese he is the initiator of the organization and creation of many orphanages and free cuisines for the needy in his diocese.
He died on 1 May 1961 in Tarnovo. He is buried in the narthex of the Nativity of the Blessed Virgin Mary Cathedral.