Tobias graduated from Harvard University in 1968 with a degree (B.A.) in Slavic languages and literatures. In 1972, he obtained his Masters of Business Administration degree from Harvard as well. During his schooling, he wrote for New York Magazine, and after graduation became a contributing editor.

Tobias is also an author. Among his titles on investment are The Only Investment Guide You'll Ever Need, The Only Other Investment Guide You'll Ever Need, My Vast Fortune, Money Angles, The Invisible Bankers: Everything the Insurance Industry Never Wanted You to Know and The Funny Money Game. Tobias also wrote the semi-autobiographical novel The Best Little Boy in the World under the pen name "John Reid" in 1973. He used a pen name because he wasn't comfortable yet with publicly disclosing his homosexuality to a broad audience. This book was later republished in 1998 under his real name to coincide with the sequel, The Best Little Boy in the World Grows Up. Despite his writing and successful investing on his own behalf, he has never been employed in the investment industry . He parlayed his writings and advice into success in the software industry as well with his Andrew Tobias's Managing Your Money financial application, which was ultimately eclipsed by Quicken.

Tobias has written on other topics with books such as Fire and Ice: The Charles Revson/Revlon Story, Getting By on $100,000 a Year, a collection of magazine pieces; Auto Insurance Alert, a book proposing radical insurance reform; Kids Say Don't Smoke on the efforts of tobacco companies to sell cigarettes to younger consumers (which was also published in Russian).

For several years he had a column in Esquire, then in Playboy, then in Time, and has frequently appeared in Parade.

He has been a strong opponent of Republican efforts to reduce taxes for high-income individuals before balancing the budget and/or funding what he considers higher priorities. His columns in 2004 were generally directed at the economic policies of President George W. Bush.

He became a controversial figure in a fight over a ballot initiative to convert California's auto insurance system into a no-fault system which would be paid for through gasoline taxes instead of premiums. He faced fire from insurance groups who feared the loss of business and profits, from insurance agents who feared the loss of commissions, from anti-tax persons who objected to financing the scheme through gasoline taxes, from oil companies that did not want higher prices to reduce demand, from consumer groups that had strongly supported "true no-fault" insurance in years past but (in Tobias's view) had caved to the influence of personal injury attorneys, and from personal injury attorneys who feared a substantial loss of income if no-fault were enacted. Although Tobias wrote a book on the topic and spearheaded the California initiative, funding a large part of it himself, he is quick to point out that neither pay-at-the-pump nor "true no-fault" (which he says Michigan comes closest to in the U.S.) is an idea original with him. In fact, at least two Canadian provinces have similar public insurance schemes.

Tobias is the partner of fashion designer Charles Nolan. Tobias was Grand Marshall of the 2005 New York City LGBT Pride Parade.