Professor of Composition at Stanford University, he obtained his PhD from the University of California in San Diego, where he studied first and foremost with Brian Ferneyhough. His solo, chamber, choral, orchestral, operatic, and electroacoustic works have been performed throughout North and South America, Europe (including major performances at the International Summer Courses for New Music in Darmstadt), Africa, Australia, and Asia. 

Many of his pieces can be characterised as challenging the conventional boundaries of music. Examples include works for three conductors and no players, a concerto for florist and orchestra, pieces for instruments made of junk, notational specifications that appear on the faces of custom wristwatches, works for an invented sign language choreographed to sound, amplified Dadaist rituals, and a 72-foot-long graphic score displayed in a museum and accompanied by no instructions for its interpretation. His TED talk on boredom has been seen by more than five million viewers. 

His works have been commissioned by Betty Freeman, Merce Cunningham Dance Company, Fromm Foundation, Kronos Quartet, Wien Modern festival, Paul Dresher Ensemble, St Lawrence String Quartet, Meridian Arts Ensemble, Chamber Music America, Spoleto Festival USA, and many others. He has engaged in many intermedia collaborations, including neural artists, film makers, florists, architects, choreographers, and laptop DJs.


He is also an accomplished jazz pianist, performing internationally from Sumatra to Wagadugu with his father, Bob Applebaum, as the Applebaum Jazz Piano Duo. His music has been released under such labels as Innova, Tzadik, Capstone, Blue Leaf, SEAMUS, New Focus, ChampdAction, and Evergreen. 

Applebaum has served on the board of Other Minds and as a trustee of Carleton College, where he gives lectures. He has also taught notably at Antwerp, Santiago, Singapore, Paris, Amsterdam, Copenhagen, Stockholm, and Oxford. He collaborates with the Atlantic Center for the Arts. In 2000 he took up work at Stanford University, where he is the director of the Stanford Improvisation Collective. He received the Walter J. Gores Award for excellence in teaching (2003) and was Hazy Family University Fellow in Undergraduate Education (2010–20). 

Selected works (since 2005): 48 Objects for 16 players (2005), The Blue Cloak for soloist and sextet (2005), Mobile for Paper for any number of performers (2005), Sixteen for 16 performers (2005),The Bible Without God, improvised work (2005), Magnetic North for soloist and brass quintet (2006), Martian Anthropology 4.5.6, chamber opera (2005), Echolalia, amplified Dadaist rituals (2006), 40 Cryptograms, graphic score (2006), Agitprop for symphony orchestra and jazz band (2006), Variations on Variations on a Theme by Mozart for tape (2006), TheComposer’s Middle Period for sextet (2007), Sock Monkey for orchestra (2007), Theme in Search of Variations I for trio (2007), On the Nature of the Modern Age for piano duo (2007), Theme in Search of Variations II for quintet (2007), Theme in Search of Variations III for quartet (2007), Medium for quartet (2008), Pause for piano (2009), Straitjacket for percussion quintet (2009), Concerto for florist and orchestra (2009), Curb Weight Surgical Field, duo for grand piano and two players (2010), The Metaphysics of Notation, graphic score (2010), Aphasia for hand gestures and tape (2010), Coat Room for octet (2012), The Second Decade for percussion quartet (2012), Rabbit Hole for octet (2012), Gone, Dog. Gone! for percussion duo (2012), 30 for 12 percussionists (2012), TheThird Decade for percussion septet (2012), Clicktrack for 12 percussionists (2014), Composition Machine #1 for percussion (2014), Speed Date for violin and cello (2014), Speed Dating for octet (2014), Wristwatch: Speed Dating (2014),Wristwatch: Control Freak for various lineups (2015), Darmstadt Kindergarten for string quartet (2015), Three Unlikely Corporate Sponsorships for tape (2016), Dead Name for string quartet (2017), Administocracy for voice, bass clarinet, trumpet and trombone (2017), Xenophobe: In Memory of Democracy for orchestra (2017), 50 Things for two violins (2017), Control Freak for various configurations of chamber musicians (2015–18), Tricks, card trick synchronised to tape (2018), List for tape (2018), Canoe Patron, PowerPoint animation with tape (2018), Springtime for Travis and Andy for electric guitar and percussion (2018), Flashlight for string quartet (2018), Venture Capital Punishment for septet with composed rituals (2020), More or Less for violin and recorded violin (2020).