Mattingly holds a BA in Classics and a BM in Music Composition from Bard College & Conservatory of Music, where he studied with George Tsontakis, Joan Tower, John Halle and Kyle Gann.

[5] Various performance groups have featured Mattingly's work, including the Los Angeles Philharmonic, Cabrillo Festival Orchestra, and the Berkeley Symphony.

Several solo artists and small ensembles have performed his work as well, including Soovin Kim, Ignat Solzhenitsyn, Sarah Cahill, Geoffrey Burleson, Mary Rowell, Other Minds, Symphony Parnassus, the Da Capo Chamber Players, and the Del Sol String Quartet.

Stranger Love, a six hour opera for 28 musicians, 8 singers, and 6 dancers, written together with a writer Thomas Bartscherer, premiered in May, 2023 at Walt Disney Concert Hall.

It was directed by Lileana Blain-Cruz, conducted by David Bloom and performed by Contemporaneous ensemble.