He grew up in Russia with his family during World War I before returning to Warsaw and completing middle school in 1935. Twardowski then began studying literature at the University of Warsaw and published his first book of poetry in 1937.
During World War II, he participated in operations with the Armia Krajowa and fought in the Warsaw Uprising. After the war, he entered the seminary and studied theology at the University of Warsaw, becoming a priest in 1948. He later became the provost of the Visitationist Church and wrote for the Catholic magazine Tygodnik Powszechny.
Twardowski gained fame in 1960 with the publication of his poetry book "The Sign of Trust" and received numerous awards throughout his career, including the PEN Club and Robert Graves lifetime achievement awards, the Order Uśmiechu, the IKAR prize, and the TOTUS prize.
He died in Warsaw in 2006 and was buried at the Temple of Divine Providence, despite his wish to be interred at the Powązki cemetery.