Hill's father was a traveling preacher and went town to town, bringing his family with him. Until she was about ten years old, Hill lived in a 32-foot camper with her father, mother and two younger brothers. While traveling with her family, Hill would often explore rivers by campgrounds. When Hill was six years old, she and her family were taking a hike one day and a butterfly landed on her finger and stayed with her the entire time. From that day on, her nickname became "Butterfly."She decided to use that as her nickname for he rest of her life.

When Hill was in middle school, her family stopped travelling and settled in Jonesboro, Arkansas. In August 1996, at age 22, Hill suffered a near-fatal car crash. At the time, Hill was acting as designated driver for a friend who had been drinking. Her friend's car was hit from behind by a drunk driver. The steering wheel of the car penetrated her skull; it took almost a year of intensive therapy before she regained the ability to speak and walk normally.

Hill embarked on a spiritual quest afterwards, leading her to the environmental cause opposed to the destruction of the redwood forests in Humboldt County, California. "The steering wheel in my head, both figuratively and literally, steered me in a new direction in my life," Hill says.

After recuperating from her accident, Hill took a road trip to California and attended a reggae fundraiser to save the forests. A group of "front-liners" had been rotating tree sitters in and out of giant redwoods in Humboldt County every couple of days to stave off Pacific Lumber Co. loggers who were clear-cutting. Organizers wanted someone to stay in the tree a week. "Nobody else would volunteer so they had to pick me," says Hill.

Originally, Hill was not officially affiliated with any environmental organization, deciding by herself to undertake the act of civil disobedience. Soon, Hill was actively supported by Earth First!, among other organizations and volunteers.

On December 10, 1997, Hill ascended 180 feet up the Redwood Tree, Luna.

Hill lived on two six-by-six-foot platforms for 738 days. Luna's trunk was her sidewalk and exercise treadmill. Hill learned survival skills while living in Luna, such as "seldom washing the soles of her feet, because the sap helped her feet stick to the branches better." Hill used solar-powered cell phones for radio interviews, became an "in-tree" correspondent for a cable television show and hosted TV crews to protest old-growth clear cutting. With ropes, Hill hoisted up survival supplies brought by an eight-member support crew. To keep warm, Hill wrapped herself tight in a sleeping bag, leaving only a small hole for breathing. For meals, Hill used a single-burner propane stove. Throughout her ordeal, Hill weathered freezing rains and 40-m.p.h. winds from El Niño, helicopter harassment, a ten-day siege by company security guards, and intimidation by angry loggers.

A resolution was reached in 1999 when the Pacific Lumber Company agreed to preserve Luna and all trees within a buffer zone. In exchange, Hill agreed to vacate the tree. In addition, $50,000 that Hill and other activists raised during the cause was given to the logging company, as stipulated by the resolution. The $50,000 Earth First! paid to Pacific Lumber was then donated to Humboldt State University as part of the agreement for research into sustainable forestry.

The tree was later cut with a chainsaw. The gash to the -tall redwood was discovered November 2000 by one of Hill's supporters. Observers at the scene said the cut measured deep and around the base, somewhat less than half the circumference of the tree. The gash was treated with an herbal remedy and the tree was stabilized with steel cables. As of spring 2007, the tree is doing well with new growth each year. Caretakers routinely climb the tree to check on its condition and to maintain the steel guywire.

Since her tree sit, Hill has become a motivational speaker (holding some 250 events a year), a best-selling author and the co-founder of the Circle of Life Foundation (which helped organize We The Planet, an eco-friendly music tour) and the Engage Network, a nonprofit that trains small groups of civic leaders to work toward social change.

On July 16, 2002, Hill was jailed in Quito, Ecuador outside the offices of Occidental Petroleum, for protesting a proposed oil pipeline that would penetrate a virgin Andean cloud forest that teems with rare birds. "The cloud forest is stunning," said Hill. "It's this deep, lush green, spangled with explosions of red, yellow and purple from the flowers, birds and insects. But the environmental destruction we saw along the pipelines that had already been built was horrendous." Ecuadorian President Gustavo Noboa commented, "The little gringos have been arrested, including the old cockatoo who climbs trees." Hill was later deported from Ecuador.

In 2003, Hill became a proponent of tax redirection, resisting payment of about $150,000 in federal taxes, donating that money to after-school programs, arts and cultural programs, community gardens, programs for Native Americans, alternatives to incarceration, and environmental protection programs. She said:

I actually take the money that the IRS says goes to them and I give it to the places where our taxes should be going. And in my letter to the IRS I said: "I'm not refusing to pay my taxes. I'm actually paying them but I'm paying them where they belong because you refuse to do so."

In 2006, Hill protested the sale of the South Central Farm in an attempt to save the 14-acre farm from developers.

In an April 2009 interview, Hill pondered what would come next for her:

The tree-sit and action since created this very particular role that Julia Butterfly Hill fulfills. And, because I'm a person committed to growth, to looking for where my edge is, that role is now too narrow for me. But it's hard to figure out what's next because there's this entire reality that's been created around this role that I play. And I'm not discounting that role - I've been able to help communities that I love very much. And at the same time, I'm looking for what's next for me, and it's so easy to stay in that role that myself and this world co-created together. But I just know that there's aspects of it that need to shed.

Hill has been the subject of several documentaries, interviews, and books, including her own memoirs, The Legacy of Luna and has influenced numerous musicians.

A benefit concert was played at the Mateel Community Center in Redway, CA during Julia's "tree sit", on December 10, 1998. Artists performing were Bob Weir and Mark Karan as an acoustic duet, the Steve Kimock Band and the Mickey Hart Band. Julia took part in the event, reading her poem "Luna" via telephone while the Mickey Hart Band was performing 'The Dancing Sorcerer'.

Hill was the subject of the 2000 documentary film Butterfly, and she is featured in the documentary film The Art of Resistance, both chronicling her time in the redwood tree.

The 12th season episode "Lisa the Tree Hugger" of The Simpsons was conceived when writer Matt Selman heard a news story about Hill.

In music

Several musicians have been inspired by Hill and her activism and written songs about her:

• Trey Anastasio and Tom Marshall wrote a song called Kissed by Mist about Julia.

• The Red Hot Chili Peppers song "Can't Stop" contains the line "J. Butterfly is in the treetop."

• In 2002 Los Suaves made a song in honor of Julia called "Julia Hill" on the "Un paso atrás" album in which the singer is "Luna".

• Also in 2002, Ozark Folk/Bluegrass artists Donna Stjerna and Kelly Mulhollan who perform as Still On The Hill released their album, "Chaos and Calm" which includes a track named "Beautiful Butterfly" based on and in honor of their fellow Arkansan, Julia Butterfly Hill.

• Neil Young made a reference to her in the 2003 song "Sun Green" on the "Greendale" album in which the title character "Still wants to meet Julia Butterfly."

• In 2009, Idina Menzel wrote a song entitled "Butterfly" referring to Butterfly's concern for the environment.

• Folk Musician Kelly Green wrote a song entitled "Julia Butterfly" inspired in part by Julia "Butterfly" Hill.

• Casey Desmond wrote a song called "Julia Butterfly Hill" which appeared on her 2006 record "No Disguise"

• Folk Musician Rachel Nelson wrote a song entitled "Julia Butterfly" in honor of Julia "Butterfly" Hill.

Film adaptation

A film adaptation of The Legacy of Luna called Luna has been announced, directed by Laurie Collyer and starring Rachel Weisz. However, the film has been stuck in development hell; Weisz has actively worked towards getting the project off the ground.

I flew out to meet her in San Francisco. She's a very strange character, a great person, and it's an incredible story, an inspirational story. I've been desperately trying to get that movie together, but right now it's very hard to get money for dramas, particularly a drama with a female at the centre of it...If you happen to know of anyone who's a philanthropist and who's interested in conservation...