Thomas Peterffy was born in Budapest, Hungary in 1944, in a hospital basement during a Russian air raid. He left his engineering studies and emigrated to the United States as a refugee in 1965. When he moved to New York City, he did not speak English. Peterffy began his career in the US as an architectural draftsman working on highway projects for an engineering firm. It was at this firm that he volunteered to program a newly-purchased computer, ultimately shaping the course of his Future. Of his background in programming Peterffy said, "I think the way a CEO runs his company is a reflection of his background. Business is a collection of processes, and my job is to automate those processes so that they can be done with the greatest amount of efficiency."

Peterffy left his career designing financial modelling software and bought a seat on the American Stock Exchange to trade equity options. During his career in Finance, he has consistently pushed to replace manual processes with more efficient automated ones. He would write code in his head during the trading day and then apply his ideas to computerized trading Models after hours. Peterffy created a major stir among traders by introducing handheld computers onto the trading floor in the early 1980s. His Business related to his AMEX seat eventually developed into Interactive Brokers.

In 1999, Peterffy was influential in persuading the Securities and Exchange Commission (SEC) that US options markets could be linked electronically, which would ensure that Investors receive the best possible options prices. He has also testified before the United States Senate Banking Subcommittee on Securities, Insurance, and Investment about adding banking regulations.

Interactive Brokers Group, Inc. (IB) is an online discount brokerage firm in the United States. The company traces its origin to 1977 when Peterffy bought a seat on the American Stock Exchange as an individual market maker, and formed T.P. & Co. the following year. IB consists of many subsidiaries operating on most major stock, futures, bonds, forex, and options exchanges worldwide. The company commenced a public offering on 4 May 2007 under the ticker symbol NASDAQ: IBKR on the Nasdaq exchange. Barron's Magazine stated in 2009 that Interactive Brokers maintains a position as "the least expensive trading venue for investors", and has held the ranking as the lowest cost broker for five straight years. An analysis of their on-line website, however, indicates many higher charges than traditional brokers (e.g., borrow rates based on security prices rounded up to the nearest dollar, as opposed to industry standard of just 102% or price, etc.)

Voter registration records in Connecticut show that Peterffy is registered as an independent voter. Campaign contribution records show that he donated at least $60,000 to the Republican National Committee in 2011 and that over the past few years has mostly donated to Republican candidates.

During the 2012 United States presidential campaign, Peterffy created political ads in support of the Republican Party. Peterffy bought millions of dollars of air time on networks such as CNN, CNBC, and Bloomberg. The ads consisted of a minute-long spot narrated by Peterffy that warned against creeping socialism in the United States. The ads were considered remarkable in part because Peterffy is not a candidate and did not buy the ads through a "527 group" but instead paid for them directly.

During the 2016 presidential election, Peterffy donated $100,000 to the campaign of Republican nominee Donald Trump.

Peterffy's net worth is estimated at $19.5 billion as of January 2018 Previously, he was the 76th richest person in the United States, and the 3rd richest in Connecticut. He is divorced with three children. He is an avid Equestrian. He lives in Palm Beach, Florida. In 2015 it was reported that he had listed his 80 acre Connecticut estate for $65 million.