Deunov was born on 11 July 1864 in Nikolaevka, Bulgaria, the third child of priest Constantin Deunovski and Dobra Georgieva. In 1872 Peter Deunov was admitted to a elementary school and he graduated from secondary school in Varna after the Liberation of Bulgaria from the Ottoman Empire. On 24 June 1886 he completed his studies at the American School of Theology in Svishtov and was a teacher in Hotantsa, near Rousse, from the autumn of 1887 to the summer of 1888.
In August 1888 he left for the USA. He was enrolled at the Drew Theological Methodist Seminary in Madison, New Jersey and completed his studies there in May 1892.
In 1895 (at the age of 31) Peter Deunov returned to Bulgaria and settled in Varna. In 1896, he published Science and Education, in which he analysed the development of humankind in the dramatic world events and wrote about the foundations of a new culture which was bound to take place during the coming century.
In 1896 he was one of the founders of the "P. R. Slaveikov" community and cultural centre, he was appointed librarian and delivered lectures to the citizens of Varna. In 1897, together with some of his followers in Varna, he founded a "Society for the Elevation of the Religious Spirit of the Bulgarian People". He published the brochure of mystic texts in the same year under the title of "Hio-Eli-Meli-Mesail".
Events from 1897 placed him at the centre of the spiritual society, which later on developed into a Synarchic Chain (1906) and into the Universal White Brotherhood (1918). After 1897 he became known as "Master Beinsa Douno". Beinsa Douno translates roughly as The One Who Brings in Good through the Word.
In 1898 he wrote and delivered the lecture, " An Appeal to My Nation", in Varna. This lecture is an appeal to social and spiritual self-identification. During the following year he wrote "The Ten Testimonies of God and The Divine Promise". From 1899 Master Beinsa Douno convened Annual Meetings in Varna, which were originally called "Meetings of the Synarchic Chain". From then onwards until 1942 the Universal White Brotherhood held its Annual Meetings at various places every year.
From 1901 to 1912 he travelled to various places in Bulgaria, delivered lectures and carried out phrenologic investigations. He started delivering his lectures in public. The historic, cosmic and metaphysical figure of Christ has a central place in his lectures. In 1912, he completed The Testament of the Colour Rays of Light
On 16 March 1914 he delivered his first Sunday talk which led to the Power and Life series. He developed the main principles of his teaching, which he called The New Teaching of the Universal White Brotherhood. On 8 February 1917 in Sofia he started a series of special lectures for married women, which lasted until 30 June 1932.
During 1917-1918, at the time of the First World War, the government of Vassil Radoslavov sent him in exile to Varna under the pretext that his teaching was weakening the spirit of the soldiers at the front. After the end of the First World War in 1918 the number of his followers all over the country grew rapidly and in the 1930s they numbered about 40,000 people.
In 1922 he opened an Esoteric School in Sofia, which he called School of the Universal White Brotherhood. In 1927 he established the settlement of Izgrev near Sofia (today a residential area of the city) where he gathered his audience, followers and disciples to have a centre where the esoteric school worked. He settled permanently in Izgrev where he delivered the various series of his Word. From 1927 he delivered a series of lectures at the annual meeting of the Universal White Brotherhood.
In 1930, he opened a new series of his teaching, called the Sunday Morning lectures, which lasted until April 1944. From 1934 he started working on the Paneurhythmy - a series of twenty-eight exercises consisting of melody, text and plastic movements. Later on he added the exercises The Sun Rays and Pentagram.
On 4 May 1936 he was attacked by a political party activist, causing brain hemorrhage and paralysis from which he recovered by the following August. On 22 March 1939 he wrote a message to his disciples titled "The Eternal Testament of Spirit." In early 1944 during the Soviet air raids on Sofia he organized the temporary evacuation of Izgrev to the village of Marchaevo. On 20 December 1944 he delivered his last lecture "The Last Word" to the General Esoteric Class. He died on 27 December 1944 and was buried in Izgrev