In 2002, Horowitz formed Michigan-based Tally Hall with Rob Cantor and Zubin Sedghi. Horowitz performed as keyboardist, writer and vocalist in the band until the band went on hiatus in 2011.

Horowitz began apprenticing under producer Dave Tozer in 2011. He spent two years working on John Legend’s gold-certified Love in the Future, which includes the 12x platinum “All of Me”. He also worked on productions for artists including needtobreathe, Celine Dion, Kai, Rebecca Ferguson, Ella Eyre and Dev.

On July 1, 2014, Andrew appeared with Rob Cantor in a video titled “29 Celebrity Impressions, 1 Original Song”, performing their song “Perfect”. A week later, Cantor released a making-of video, demonstrating that his impressions were a hoax done through audio and video editing, and in fact featured 11 different impressionists. As of December 2017, the video has 17 million views, and the corresponding explanation video has 2.4 million views.

As a writer and producer, Horowitz has become a presence in the NY music scene. He’s worked with LP, Kara Dioguardi, Amanda Brown, Gala, morgxn, Phebe Starr, Carrie Manolakos, Janelle Kroll, Kat Cunning, Crystal Monee Hall and Sash, amongst others.

He currently works out of his studio in Williamsburg, Brooklyn.