Janis Joplin was born at St. Mary Hospital in Port Arthur, Texas, the daughter of Seth Ward Joplin and Dorothy Bonita East. Her father was an engineer at Texaco.

Janis had two younger siblings, Michael and Laura. As a teenager, she befriended a group of outcasts, including Jim Langdon and Grant Lyons, the latter of whom played her the blues for the first time. She began listening to musicians such as Leadbelly, Bessie Smith, Odetta, and Big Mama Thornton and singing in the local choir. While at Thomas Jefferson High School, she was mostly shunned. Among her high school classmates was another individual destined for stardom: future college and NFL coach Jimmy Johnson. In a 1992 Sports Illustrated profile of his career, Johnson claimed that he gave Janis the high school nickname of "beat weeds." Primarily a painter, it was in high school that she first began singing blues and folk music with friends. Joplin graduated from high school in 1960 and attended the University of Texas in Austin, though she never attained a degree. One persistent story is of her being nominated in a Fraternity contest "The Ugliest Man on Campus."

Cultivating a rebellious manner that could be viewed as "liberated" — the women's liberation movement was still in its infancy at this time — Joplin styled herself in part after her female blues heroines, and in part after the beat poets. She left Texas for San Francisco in 1963, lived in North Beach and in Haight-Ashbury as well as Corte Madera. Around this time her drug use began to increase, and she acquired a reputation as a "speed freak" and occasional heroin user. She also used other intoxicants. She was a heavy drinker throughout her career, and her trademark beverage was Southern Comfort.