O'Malley has said that he grew up surrounded by Irish music. While attending Gonzaga College High School in Washington D.C. in 1979, O'Malley and his football coach Danny Costello formed a band, Shannon Tide, which played Irish music and folk rock. After graduating from University of Maryland Law School, O'Malley went solo for a year. In 1988, he founded the Baltimore-based Celtic rock band O'Malley's March, in which he is still the lead singer and plays acoustic guitar and penny whistle. In addition to Irish music, the band's mainstays include Johnny Cash's "Ring of Fire," Woody Guthrie's "This Land Is Your Land," the parlor song "Hard Times Come Again No More," The Pogues ' "Body of an American" and Passenger's "Scare Away The Dark". During O'Malley's mayoralty he wrote and performed a number of songs celebrating his adopted city and its strong Irish heritage. As the bicentennial of the War of 1812 approached in 2012-2015, while still Governor as he and his compatriots celebrated the British defeat in the "Battle for Baltimore" and other musical numbers at a stirring concert in Patterson Park in East Baltimore on the anniversary of the land and sea attack on Defenders' Day in September 2014. In addition to more traditional venues, the band performs for O'Malley's campaign events. In 2012, it played at the White House for 44th President Barack Obama as part of an extended Saint Patrick's Day celebration honoring Irish Prime Minister Enda Kenny. O'Malley's March continues to perform following O'Malley's decision to end his 2016 presidential campaign. Through O'Malley's March, he has become close to Leo Moran and other members of The Saw Doctors.