Galvin was born on January 8, 1950, the son of a fireman. He attended Catholic schools, Fordham University and Fordham University School of Law. He previously worked as hearing officer for the New York City Department of Sanitation.
Galvin was the publicity director for the New York-based NORAID, an Irish American group fundraising organization which raised money for the families of Irish republican prisoners, but was also accused by the American, British, and Irish governments to be a front for the supply of weapons to the Provisional IRA.
Galvin became a publisher of The Irish People in the 1980s. He was banned from Northern Ireland because of a speech he gave that seemed to endorse terrorism. In August 1984 he defied the ban, and entered Northern Ireland from the Republic of Ireland. The following year Galvin returned to Northern Ireland to attend a funeral for an IRA member killed when a makeshift grenade launcher he was trying to fire at a Royal Ulster Constabulary barracks exploded. In 1989 Galvin was arrested and deported for violating the exclusion ban yet again.
Galvin has criticised the Northern Ireland peace process as a betrayal of republican ideals, and characterized IRA's decision to open up its arms dumps to Independent International Commission on Decommissioning inspectors as a surrender.
- "How the peace train pulled out without Martin Galvin". Belfast Telegraph. May 24, 2010.
- "America's Leading Ira Supporter, Martin Galvin, Says He "Understands" Why Terrorists Targeted Mrs. Thatcher". People. September 5, 1984.
- "Martin Galvin's Message". The New York Times. August 15, 1984.
- Reference to Martin Galvin, Jr., Cdn.pagesuite.com; accessed June 10, 2014.
- Wedding of Martin Galvin, Jr. and Emer Larkin, Riverdalepress.com; accessed June 10, 2014.
- Pike, John. "Northern Ireland: The Time And Place For Urban Terror". Globalsecurity.org. Retrieved 2017-03-12.
- Pike, John. "IT0468 App A". Globalsecurity.org. Retrieved 2017-03-12.
- "Rep. King and the IRA: The End of an Extraordinary Affair? - The New York Sun". Globalsecurity.org. Retrieved 2017-03-12.
- "American Defies Ban and Attends IRA Services". Los Angeles Times. August 10, 1985.
- "Pro-IRA American Seized in Ulster; Had Been Barred". Associated Press. August 16, 1989.
- "'Traitors' — Martin Galvin's Rap for "Sell Out" by Sinn Féin". Sunday World. June 19, 2011.
- "Republican rebels gain strength". The Observer. June 24, 2000.
- Eamon Sweeney (2016-05-31). "SAS killing: Martin Galvin praises 'true patriot' McBrearty". Derry Journal. Retrieved 2017-03-12.