In 1959, Baldessari began teaching art in the San Diego school system. He kept teaching for nearly three decades, in schools and junior colleges and community colleges, and eventually at the university level. When the University of California decided to open up a campus in San Diego, the new head of the Visual Art Department, Paul Brach, asked Baldessari to be part of the originating faculty in 1968. At UCSD he shared an office with David Antin. In 1970, Baldessari moved to Santa Monica, where he met many artists and Writers, and began teaching at CalArts. His first classes included David Salle, Jack Goldstein, Mike Kelley, Ken Feingold, Tony Oursler, James Welling, Barbara Bloom, Matt Mullican, and Troy Brauntuch. While at CalArts, Baldessari taught "the infamous Post Studio class", which he intended to "indicate people not daubing away at canvases or chipping away at stone, that there might be some other kind of class situation." The class, which operated outside of medium-specificity, was influential in informing the context for addressing a student's art practice at CalArts. He quit teaching at CalArts in 1986, moving on to teach at UCLA, which he continued until 2008. At UCLA, his students included Elliott Hundley and Analia Saban.
Baldessari was born in National City, California to Hedvig Jensen, a Danish nurse, and Antonio Baldessari, an Italian salvage dealer. Baldessari and his elder sister were raised in Southern California. He attended Sweetwater High School and San Diego State College. Between 1960 and 1984, he was married to Montessorian Teacher Carol Ann Wixom; they have two children.
Baldessari set a personal auction record when his acrylic-on-canvas piece Quality Material (1966–1968) was sold for $4,408,000 at Christie's New York in 2007.
Another work, Painting for Kubler (1967–68) presented the viewer theoretical instructions on how to view it and on the importance of context and continuity with previous works. This work referenced art Historian George Kubler's seminal book, The Shape of Time: Remarks on the History of Things. The seemingly legitimate art concerns were intended by Baldessari to become hollow and ridiculous when presented in such a purely self-referential manner.
Baldessari has been in over 200 solo shows and 1,000 group shows in his six-decade career. He had his first gallery solo exhibition at the Molly Barnes Gallery in Los Angeles in 1968. His first retrospective exhibition in the U.S. in 1981 was mounted by the New Museum of Contemporary Art in New York, and traveled to the Contemporary Arts Center, Cincinnati, the CAM, Houston, the Van Abbemuseum, Eindhoven, and the Museum Folkwang, Essen.
Much of Baldessari's work involves pointing, in which he tells the viewer not only what to look at but how to make selections and comparisons, often simply for the sake of doing so. Baldessari's Commissioned Paintings (1969) series took the idea of pointing literally, after he read a criticism of conceptual art that claimed it was nothing more than pointing. Beginning with photos of a hand pointing at various objects, Baldessari then hired amateur yet technically adept artists to paint the pictures. He then added a caption "A painting by [painter's name]" to each finished painting. In this instance, he has been likened to a Choreographer, directing the action while having no direct hand in it, and these paintings are typically read as questioning the idea of artistic authorship. The amateur artists have been analogized to sign Painters in this series, chosen for their pedestrian methods that were indifferent to what was being painted. Baldessari critiques formalist assessments of art in a segment from his video How We Do Art Now (1973), entitled "Examining Three 8d Nails", in which he gives obsessive attention to minute details of the nails, such as how much rust they have, or descriptive qualities such as which appears "cooler, more distant, less important" than the others.
Originally conceived in 1970, Unrealised Proposal for Cadavre Piece would have visitors look through a peep-hole and see a dead male body laid out with its feet towards them inside a climate-controlled vitrine, made to resemble Andrea Mantegna’s painting, The Lamentation over the Dead Christ (1480). Hans Ulrich Obrist, the co-director of London’s Serpentine Gallery and Klaus Biesenbach, the Director of MoMA PS1, first attempted to realize Baldessari’s idea in 2011 and the resulting paperwork of failed attempts to procure a willing male cadaver was displayed in the exhibition "11 Rooms" at the Manchester International Festival.
Baldessari's film Police Drawing documents a 1971 performance, Police Drawing Project. In this piece, the Artist walked into a class of art students who had never seen him, set up a video camera to document the proceedings, and left the room. Subsequently, a police Artist entered and, based on the students' testimony, sketched a likeness of the Artist. In the black-and-white video I Am Making Art (1971), Baldessari stands facing the camera; for nearly 20 minutes, he strikes and then holds various poses — crossing his arms over his chest or swinging one arm out to one side or pointing directly at the lens, for Example — and with each new gesture, he states "I am making art." In a 1972 tribute to fellow Artist Sol LeWitt, Baldessari sang lines from LeWitt's thirty-five statements on conceptual art to the tune of popular songs. Other films include Teaching a Plant the Alphabet and the Inventory videos, also from 1972.
In 1972, Ileana Sonnabend agreed to represent him worldwide. In 1999, after twenty-six years with the Sonnabend Gallery, Baldessari went to Marian Goodman. He is also represented by Margo Leavin, Los Angeles (since 1984), and Sprüth Magers, Berlin/London.
Baldessari has expressed that his interest in language comes from its similarities in structure to games, as both operate by an arbitrary and mandatory system of rules. In this spirit, many of his works are sequences showing attempts at accomplishing an arbitrary goal, such as Throwing Three Balls in the Air to Get a Straight Line (1973), in which the Artist attempted to do just that, photographing the results, and eventually selecting the "best out of 36 tries", with 36 being the determining number just because that is the standard number of shots on a roll of 35mm film. The Writer eldritch Priest ties John Baldessari's piece Throwing four balls in the air to get a square (best of 36 tries) as an early Example of post-conceptual art. This work was published in 1973 by a young Italian publisher: Giampaolo Prearo that was one of the first to believe and invest in the work of Baldessari. He printed two series one in 2000 copies and a second more precious reserved to the publisher in 500 copies. Following Baldessari’s seminal statement “I will not make any more boring Art”, he conceived the work The Artist Hitting Various Objects with a Golf Club (1972–73), composed of 30 photographs of the Artist swinging and hitting with a golf club objects excavated from a dump, as a parody of cataloging rather than a thorough straight classification.
A riff on his 1977 color video Six Colourful Inside Jobs, in Thirteen Colorful Inside Jobs (2013) a room is repainted by a performer in a different colour every day for the duration of the exhibition, carefully following the instructions of the Artist.
Retrospectives of his work was shown at MOCA, Los Angeles, which traveled to SFMOMA, the Hirshhorn Museum and Sculpture Garden, the Whitney Museum and the Musée d'Art Contemporain, Montreal in 1990-92; at Cornerhouse, Manchester, and traveled to London, Stuttgart, Ljubljana, Oslo, and Lisbon in 1995-96 entitled "This Not That"; and Pure Beauty opened at the Tate Modern, London, in 2009 and travelled to MACBA, Barcelona; LACMA, Los Angeles; and The Metropolitan Museum of Art, New York, through 2011.
There was an "Artist's Choice: John Baldessari" at the Museum of Modern Art in 1994, and the Artist was invited to curate the exhibition "Ways of Seeing: John Baldessari Explores the Collection" at the Hirshhorn Museum and Sculpture Garden in 2006, and he created the exhibition design for "Magritte and Contemporary Art: The Treachery of Images" at the Los Angeles County Museum of Art.
In "Double Bill", a 2012 series of large inkjet prints, Baldessari paired the work of two selected artists (such as Giovanni di Paolo with David Hockney, or Fernand Léger with Max Ernst) on a single canvas, further altering the appropriated picture plane by overlaying his own hand-painted color additions. Baldessari then names only one of his two artistic “collaborators” on each canvas’s lower edge, such as …AND MANET or …AND DUCHAMP.
In 2013, the California Institute of the Arts opened its John Baldessari Art Studio Building, which features approximately 7,000 square feet of space—much of it used as studio space for art students and faculty.
For the 2017/2018 season at the Vienna State Opera he designed the large-scale image (176 m²) "Graduation" for the ongoing series "Safety Curtain", conceived by museum in progress.