Born in Palolo, and raised by his mother and father, Helene and Spark Matsunaga, Matt Matsunaga grew up in suburban Washington, D.C. while his father served in Congress and as a U.S. Senator. He earned his law degree from the Georgetown University Law Center, and returned to Hawaii in 1985 to join the law firm of Carlsmith Ball, where he became a partner. From 1992 – 2002, Matthew served as a senator in the Hawaii State Legislature, where he was recognized for his effectiveness, accomplishments, and responsiveness. Matt won the Democratic primary election for Lieutenant Governor in 2002 with the most votes of any candidate in that election. He ran for Congress in the 2003 Special Election, finishing a close second. Currently, Matt is a partner with Schlack Ito Lockwood Piper & Elkind, where he specializes in business law.

Matt was named 2000 Legislator of the Year by the Mental Health Association of Hawaii, as well as "Best Legislator of the Year-1997" and one of the six best legislators in 1998 by the Honolulu Weekly. He also has been honored by the Japan-U.S. Science, Technology & Space Applications Program, the Domestic Violence Clearinghouse and Legal Hotline, Mothers Against Drunk Driving, the Junior League of Honolulu, the Hawaii Jaycees, and other civic and community organizations.

Matt has two children and has lived in District 5 for over 16 years, he currently resides in Moiliili.