Matthew Macklin was born on 14 May 1982 in Birmingham, England, to Irish parents — his father from County Roscommon and his mother from County Tipperary. He and his brother Seamus, also a boxer, spent childhood summers in Tipperary, where Matt learned hurling and remains an avid supporter of Tipperary GAA today. He holds dual British-Irish citizenship and competed under both flags during his career.

He attended the independent Solihull School and, while studying law at Coventry University, won the 2001 national ABA welterweight title as an amateur. He turned professional later that year, going on to win the Irish middleweight title (2005–2006), the British title (2009), and the European title (2009–2011).

Matt challenged for world titles three times between 2011 and 2013 — against Felix Sturm (WBA), Sergio Martínez (The Ring), and Gennadiy Golovkin (WBA) — but was defeated in each. He retired in 2016 with a professional record of 35 wins, 6 losses, and 22 knockouts.

Since retiring, Matt has built a career as a Sky Sports Boxing pundit and co-commentator, and co-hosts the popular boxing podcast Macklin’s Take alongside Andy Clarke. He also spent time in boxing management, co-founding MTK Global with Daniel Kinahan — a connection that drew scrutiny after U.S. sanctions were placed on Kinahan, and Macklin was reportedly denied entry to the US as a result; he has since distanced himself from that chapter of his career.