Alden Nowlan was born into rural poverty in Stanley, Nova Scotia, close to the small town of Windsor, Nova Scotia, along a stretch of dirt road that he would later refer to as Desolation Creek. His father, Gordon Freeman Nowlan, worked sporadically as a manual labourer.

His mother, Grace Reese, was only 14 years of age when Nowlan was born, and she soon left the family, leaving Alden and her younger daughter Harriet, to the care of their paternal grandmother. The family discouraged education as a waste of time, and Nowlan left school after only four grades. At the age of 14, he went to work in the village sawmill. At the age of 16, Nowlan discovered the regional library. Each weekend he would walk or hitchhike eighteen miles to the library to get books, and secretly began to educate himself. "I wrote (as I read) in secret." Nowlan remembered. "My father would as soon have seen me wear lipstick."

At 19, Nowlan's artfully embroidered résumé landed him a job with The Observer, a newspaper in Hartland, New Brunswick. While working at the Observer, Nowlan began writing books of poetry, the first of which was published by Fredericton's Fiddlehead Poetry Books.

Nowlan eventually settled permanently in New Brunswick. In 1963, he married Claudine Orser, a typesetter on his former paper, and moved to Saint John with her and her son, John, whom he adopted. He became the night editor for the Saint John Telegraph Journal and continued to write poetry. In 1967, he was awarded a Guggenheim Fellowship, and his collection Bread, Wine and Salt, was awarded the Governor General's Award for Poetry.

In 1966, Nowlan was diagnosed with throat cancer. His health forced him to give up his job, but at the same time the University of New Brunswick in Fredericton offered him the position of Writer-in-Residence. He remained in the position until his death on June 27, 1983.

Nowlan's most notable literary achievements include the Governor General's Award for Bread, Wine and Salt (1967) and a Guggenheim Fellowship. He was the Writer-in-Residence at the University of New Brunswick in Fredericton from 1968 until his death in 1983, and has a provincial poetry award named in his honour.

Nowlan is one of Canada's most popular 20th-century poets, and his appearance in the anthology Staying Alive (2002) has helped to spread his popularity beyond Canada.

In the 1970s, Nowlan met and became close friends with theatre director Walter Learning. The two collaborated on a number of plays, including Frankenstein, The Dollar Woman, and The Incredible Murder of Cardinal Tosca.

The home of the Graduate Student Association at the University of New Brunswick is called the Alden Nowlan House.

Nowlan is buried in the Poets' Corner of the Forest Hill cemetery in Fredericton, New Brunswick.