Frommer was raised in Jefferson City, Missouri, moving to Brooklyn, New York when he was 14. He graduated from New York University in 1950 with a political science degree, and graduated with honors from Yale Law School, where he was an editor of the Yale Law Journal. Frommer was drafted into the United States Army during the Korean War, but was posted to Europe.

While serving in Germany, he wrote and self-published a guidebook called The GI's Guide to Traveling In Europe in 1955. It sold well, and in 1957 Frommer followed up with a civilian version called Europe on 5 Dollars a Day, which covered major European urban destinations. During his vacations while a litigation associate at the law firm of Paul, Weiss, Rifkind, Wharton & Garrison, he continued his travel writing and publishing. The first guide books included Europe, New York, Mexico, the Caribbean, and Los Angeles-San Francisco-Las Vegas, expanding through the years to more than 350 titles. In 1961, Frommer founded wholesale tour operator $5-a-Day Tours, Inc. He left law practice in 1962 to pursue his travel business Arthur Frommer International, Inc., of which he was chairman and president until 1981. In 1969 Mr. Arthur Frommer built his first hotel in Amsterdam on the premises of the Weaver's Guild (in the Noorderstreet). This hotel is now known as the Hotel Mercure Amsterdam Arthur Frommer (part of the Accor group).

Frommer sold the travel guide book business to the publishing house Simon & Schuster in 1977. After several subsequent sales, the Frommer’s series was purchased by John Wiley & Sons in 2001.

He preserves a consultant role with Wiley in the Frommer's line of travel guides, leaving time to pursue other projects. Frommer kept a strong commitment to low-budget and alternative travel and to consumer advocacy in travel. In the 1980s, he published Frommer's New World of Travel, which advocated alternative vacation styles, and founded Budget Travel magazine. He writes a twice weekly column on travel which appears in over 60 newspapers across the US, and recently branched out by creating his own magazine on shopping called Arthur Frommer's Smart Shopping.

Frommer was portrayed by actor Patrick Malahide (an English actor) in the film EuroTrip.