While living with his family in Cambridge, UK during middle school, Fain studied under Haroutune Bedelian at the Royal Conservatory of Music in London.

[4] In 2007, Fain performed Aaron Jay Kernis' violin concerto Lament and Prayer with the Baltimore Symphony Orchestra, conducted by Marin Alsop.

[7] Fain reunited in 2006 with musicians from his alma mater, Curtis Symphony Orchestra, to perform Beethoven's Violin Concerto in D Major, conducted by Otto-Werner Mueller in Philadelphia at the Kimmel Center.

In 2009, Tim was a soloist in Mendelssohn Concerto for Violin and Piano (with Italian pianist Mariangela Vacatello) with iPalpiti orchestra of international laureates/ Eduard Schmieder, conductor, at Walt Disney Concert Hall in Los Angeles.

[14][15] In 2018, Fain performed Glass’ Double Concerto for Violin and Cello, conducted by Marin Alsop, with cellist Matt Haimovitz at the Cabrillo Festival.

[17] Fain made his debut with the San Francisco Symphony in April 2023, performing on the orchestra's Soundbox series curated by composer Nicholas Britell and film director Barry Jenkins.

[18] In 2010, Fain co-arranged the onscreen music in the movie Black Swan, and also performed featured violin on-camera alongside leading actress Natalie Portman in the film.

Fain also contributed featured violin performances to West Dylan Thordson's score for M. Night Shyamalan's 2019 psychological superhero thriller, Glass.

He has collaborated with other prominent musicians in performances of Glass’ work, including Iggy Pop, Simone Dinnerstein, Sondre Lerche, Lou Reed, and Bryce Dessner of The National.

[26] In 2012, Fain performed Philip Glass's Pendulum with pianist Bruce Brubaker at the composer's 75th birthday party concert in New York.

[37] Fain composed the score and performed on the soundtrack to the 2014 documentary Untouchable: Children of God which deals with the lives of two young girls who were rescued from working in Indian brothels.

[38] In 2015, Fain composed Resonance, a short work for violin and orchestra which was used for a Google Jump VR music film directed by Jessica Brillhart.

[41][42] Fain released his track Glacial in honor of Earth Day 2020, as a celebration of our planet and a call to action to combat climate change.