Welch published and performed widely during the 1960s. He taught a poetry workshop as part of the University of California Extension in San Francisco from 1965 to 1970.
Welch was born in Phoenix, Arizona and moved with his mother and sister to California in 1929. He enlisted in the Army Air Corps in 1944 but never saw active service. He worked for a period before attending Stockton Junior College, where he developed an interest in the works of Gertrude Stein.
In 1948, Welch moved to Portland, Oregon to attend Reed College. There he roomed with poets Gary Snyder and Philip Whalen. Welch decided to become a writer after reading Gertrude Stein's long story "Melanctha."  Welch wrote his thesis on Stein and published poems in student magazines. William Carlos Williams visited the college and met the three poets. He admired Welch's early poems and tried to get his Stein thesis published.
After college, Welch moved to New York City, where he worked writing copy in the advertising industry. Welch was said to have come up with the advertising slogan,"Raid Kills Bugs Dead", but others have questioned this claim. During this time, Welch started to display emotional and mental problems and went to Florida to take a course of therapy.
He then went to the University of Chicago, where he studied philosophy and English. In Chicago, he joined the advertising department of Montgomery Ward. He was working there at the time of the famous poetry reading at the Six Gallery in San Francisco that launched what was to become known as the San Francisco Renaissance.
Wanting to get back to poetry, Welch applied for a transfer to Montgomery Ward's Oakland headquarters. After the return to California, he started to get involved in the San Francisco literary scene. He soon gave up advertising and earned a living driving a cab while devoting more time to writing. He became an active participant in Beat culture, living at various times with Snyder and Lawrence Ferlinghetti. In 1960, poet Lenore Kandel met Welch and Snyder, who introduced her to many people in the Beat movement.
Jack Kerouac based his character Dave Wain in his novel Big Sur (1962) on Welch. In 1968, Welch signed the "Writers and Editors War Tax Protest" pledge, vowing to refuse tax payments in protest against the Vietnam War.
On May 23, 1971, Welch walked out of poet Gary Snyder's house in the mountains of California, leaving behind a suicide note. He had carried a stainless steel Smith & Wesson .22 caliber revolver. His body was never found.
sufficiently impressive to Jack Kerouac, who modeled his Big Sur character Dave Wain after the hard-drinking poet