He was born on 21 or 23 November (6 December) 1812 in the village of Bolshaya Lipovitsa, Tambov Province, into a devout family: his grandfather had been a priest, his father, Mikhail Fyodorovich, a sexton. He was the sixth of eight children.
In 1825 the twelve-year-old Sasha Grenkov entered the Tambov church school, from which he graduated with distinction.
From 1830 to 1836 he studied at the Tambov Seminary. In his final year there he came through a dangerous illness, vowing to become a monk if he recovered.
On 8 October 1839 he arrived at the Optina Hermitage, where the elder Leo (Nagolkin) received him kindly and took him on as his cell attendant. Before long he was tonsured and given the name Ambrose, after St. Ambrose of Milan.
In the summer of 1841 he was tonsured a riassophore monk; in 1842, into the mantle.
In 1843 he was ordained a hierodeacon. On 7 December of that year, on the road to Kaluga, he caught a chill and fell gravely ill. On 9 December 1845 he was ordained a hieromonk, though illness left him scarcely able to serve. He was later tonsured into the great schema without a change of name.
He reposed on 10 (23) October 1891 at the Shamordino convent.
Engraved on his marble gravestone are the words of the Apostle Paul: "To the weak became I as weak, that I might gain the weak: I am made all things to all men, that I might by all means save some" (1 Corinthians 9:22).