He was educated as a musician, specializing in piano, and was partly self-taught and mentored by his father, who was a professor at the University of Bonn.

[4] Like much of the mid-19th century U.S. music industry, Werlein showed little respect for copyright during his career.

In 1860, he published unauthorized sheet music for the blackface minstrel hit, "Dixie".

Only the threat of legal action convinced Werlein to credit Dan Emmett as the song's writer and to pay royalties to Firth, Pond & Co. Emmett, perhaps sardonically, dedicated the "Dixie" sequel, "I'm Going Home to Dixie", to Werlein in 1861.

He also profited from pro-Confederate sentiment by publishing several pieces of music attributed falsely to Jefferson Davis.

After the Union Army took control of New Orleans, Werlein refused to take the Oath of Allegiance required of people in occupied regions of the southern United States.

Following his refusal, Werlein went into forced retirement in New Iberia, Louisiana, until the cessation of hostilities in the American Civil War.

Werlein's for Music expanded to become a regional chain of stores, which continued in the Greater New Orleans area until its liquidation in 2003.

Philip Jr. became an owner and manager of the music store and publishing company at the end of the United States Civil War.