After six years as a general assignment reporter and business news writer for The Associated Press in Miami and New York, Merzer joined The Miami Herald in 1979 as a business writer. He became The Herald's Jerusalem bureau chief in late 1983, spending more than two years in the Middle East, and later served as a national correspondent and as a member of the newspaper’s enterprise team.
He then became The Herald's senior writer, specializing in deadline news events, and had primary responsibility for hurricane coverage. In recent years, he also gravitated to The Herald’s website, specializing in online news writing and helping the newspaper develop its online style and protocols. In the aftermath of the terrorist attacks of Sept. 11, he moved to Washington for four months and served The Herald and parent company Knight Ridder as the primary anchor of the coverage of 9/11 and war in Afghanistan. He later spent a month in Israel reporting on the wave of suicide bombings and retaliatory actions there.
In 2003, he served as Knight Ridder’s main anchor for the Iraqi War, again spending four months in the Washington bureau. He twice returned to Washington in 2005 to anchor the company’s coverage of Hurricanes Katrina and Rita.
After retiring from The Miami Herald in May 2008, Merzer started his own firm, Martin Merzer Creative Services Inc. Recent clients include: The Children's Movement of Florida, Knight Foundation, The Children's Trust, The W.K. Kellogg Foundation, Bendixen & Amandi, The Lastinger Center for Learning/University of Florida, CreditCards.com, The Associated Press, McClatchy Newspapers, The Miami Herald and Ron Sachs Communications.
During his newspaper career, Merzer covered the unraveling of National Airlines, Eastern Airlines, Pan American World Airways and Air Florida, the civil war in Beirut, the famine in Ethiopia and the Sudan, the Challenger disaster and the space shuttle’s return to flight, Hurricane Andrew, the Gulf War and the Scud missile attacks on Israel, the assassination of Israeli Prime Minister Yitzhak Rabin, the Mars Pathfinder mission, John Glenn’s return to flight, the entire 37-day impasse in Florida’s 2000 presidential election, and a wide variety of other stories.
In 1992, his work during Hurricane Andrew helped The Herald win the Pulitzer Prize for Public Service. In 2000, his work during the Elian Gonzalez affair helped The Herald win another Pulitzer Prize.
He is the main author of The Miami Herald Report: Democracy Held Hostage, a book published in June 2001 by St. Martin’s Press.
He is co-author of the Crisis Communications Handbook, published in 2003 by Jane’s Information Group.
He is co-author with Miguel “Mike” Benito Fernandez of Humbled by The Journey: Life Lessons for My Family…and Yours, a book published in 2014 by Story Farm.