He was a serf of Prince Alexei Borisovich Golitsyn, but in Moscow, he engaged in trade and contracting work, which allowed him to accumulate significant funds and become a merchant.

Around 1770, he adopted the Old Believer faith of the Fedoseevsky type and was re-baptized by a Yaroslavl peasant, Ilya Ivanov, changing his name from 'Vasily' to 'Ilya'.

His activities gained great significance in 1771 when a plague broke out in Moscow, causing panic and fears that residents would flee to other cities, spreading the infection. On September 1, 1771, a decree was issued calling for residents to organize checkpoints and quarantines around Moscow to control exits from the city. Kovylin and his fellow schismatic, merchant Zen'kov, decided to take this opportunity and offered to organize a quarantine at their own expense. After receiving permission, they rented a plot of land from the peasants of the village of Cherkizovo, through which the road to Vladimir passed, and established a checkpoint, building several houses to detain those leaving Moscow. Subsequently, the Moscow Preobrazhensky Cemetery formed around this settlement.

With the funds from Kovylin and Zen'kov, an entire town was built with chapels and stone residential buildings, which remained their private property for a long time.

The organizers of the checkpoint took care of the detainees, providing them with everything necessary, caring for the sick, and burying the deceased with church rites, unlike in most cases in Moscow, where the dead were simply buried in the ground. This made a strong impression and helped Kovylin attract many to the Old Believer faith, where re-baptisms constantly occurred during the quarantine. The Moscow authorities at that difficult time were unable to monitor violations of the law, and Kovylin's selfless activities ensured him protection from the authorities. He actively worked on strengthening the schismatic community, moved the houses of the deceased to the occupied land, and convinced many survivors to stay there.

Kovylin was elected the head of the community and enjoyed great influence, skillfully attracting the wavering with strict and passionate teachings, while interpreting religious requirements to allow for indulgence for the skeptics. In the first year, he organized the settlement, acquired many old icons, and introduced a charter obtained from the Vekta. Kovylin attracted wealthy benefactors and got along with the authorities, so that during Catherine II's reign, the community thrived.

Emperor Paul I was unfriendly towards the community, and his decrees could have led to its destruction, but Kovylin managed to delay their implementation in Moscow.

With the ascension of Alexander I, better times returned. In the first year of his reign, Kovylin, through Prince A. B. Kurakin, achieved a decree on October 15, 1801, favorable to the schismatics, which brought him fame and honor among the Old Believers. He also secured recognition of the Preobrazhensky Cemetery as a civil institution, subordinate only to the police, ensuring its prosperity. By the end of Kovylin's life, the cemetery had up to 10,000 parishioners, and up to 1,500 people lived on its territory.

Kovylin died in 1809 at an advanced age, surrounded by the respect of the community. He was buried at the Preobrazhensky Cemetery, to which he bequeathed his capital. His grave has been preserved in the center of the old part of the cemetery, behind the Nikolskaya chapel. His memory remains in the name of Kovylinsky Lane in the Preobrazhenskoe area.

Contemporaries described him as a tall man with a beautiful physique, a white elongated face, a cheerful and piercing gaze, and a long beard adorned with gray hairs. He was an outstanding man in his administrative abilities and energy. However, even the Old Believers acknowledged that he was not distinguished by the strictness of life, proclaiming the principle: 'what is done in secret is judged in secret' and allowing himself and others indulgence, only ensuring that temptation did not become apparent. Kovylin also left behind several messages on religious issues, but they are of little interest.