John was born to June Gallagher and John Gallagher Sr. who are folk musicians. He has two older sisters with whom he was raised in Wilmington, Delaware. Gallagher Jr. is as talented an actor as he is a musician. He began acting as a child artist when he portrayed the character of Tom Sawyer at Delaware Children’s Theatre. His musical journey has been strengthened as he has been a part of many bands like What Now, Not Now Murray, Annie’s Autograph and Old Springs Pike.
He worked on Broadway while he was a part of Old Springs Pike, the band which changed its name to The Springs Standard after he left the band. He did three plays by David Lindsay-Abaire- Kimberly Akimbo, which was a hit; Fuddy Meers, which wasn’t taken well by the audience;
, which served as his Broadway debut. He has also been seen in the Manhattan Theatre Club for its production, Current Events. The highlight of the beginning of his career was his role in Spring Awakening as Moritz Stiefel.
He performed the role in workshops and also in places other than Broadway. When it finally opened on Broadway, he bagged a Tony Award for Best Performance by a Featured Actor in a Musical. He performed in dramas, Port Authority and Farragut North, which were performed in the same theater in which Spring Awakening was performed. The dramas were the production of the same theater, which is the Atlantic Theater Company. John was seen in the musical based upon a Green Day album which had the same name, American Idiot. The show was initially set off-Broadway for a few months.
Just like it happened with Spring Awakening, this show also won two out of three Tony Awards when it premiered on Broadway. The next Broadway he did was that of the Royal Court Theater. The production, named Jerusalem, opened in April 2011, and he worked with it until July 2011. Gallagher is expected to return to Broadway in 2016 with a production called Long Day’s Journey into Night, along with three friends. Apart from Broadway and plays, he has also appeared in several TV series and films.
Some of the famous TV series that he appeared on are The West Wing, Law & Order, Ed, Love Monkey, etc. and also in a miniseries called Olive Kitteridge which is based on a novel. He has also been featured in several movies like Whatever Works,
, Pieces of April, Margaret, etc. He has also played a lead in Short Term 12. His most recent release is the movie The Heart Machine, which was released in April. The next expected one may be released in 2016 and is called 10 Cloverfield Lane.
On the musical front, his debut album was released in 2016 and is called Six Day Hurricane. He had been planning on releasing an album for a long time as he has been writing music since a young age. He also performs frequently in live spaces.