Birinyi was born in Hungary but moved to Pennsylvania at the age of seven. He graduated from the University of North Carolina at Chapel Hill, in 1966, with a major in history, and has an MBA from the New York University Graduate School of Business.
He started his career in the investment industry as a trader, and then worked at Salomon Brothers starting from 1976 as an equity researcher and market analyst, later being promoted to head of Equity Market Analysis. In that position he constructed the Stock Week – a weekly commentary containing studies on fund flow, market structure, volatility etc. He helped establish the Salomon-Russell International Index.
Birinyi launched Birinyi Associates in 1989, following his departure from Salomon Brothers. While founder and director of the firm, he still worked for Deutsche Bank Securities as Global Trading Strategist from 1988 until 2002.
Through his work at Birinyi Associates, Inc., he established a stock market research firm that analyzes the psychology and history of the stock market and the actions of investors in order to predict stock trends. He often makes contributions to Forbes (where he was also a columnist), Wall Street Journal, Barron's, BusinessWeek and Bloomberg Personal Finance. He has appeared as a guest on CNBC and Bloomberg TV, and was also a panelist for Louis Rukeyser’s Wall $treet Week.
He is the author of The Master Trader: Birinyi's Secrets to Understanding the Market (2013, ISBN 978-1118774731 -- a book which, According to WorldCat, is held in 508 libraries  ) and The Equity Desk – a book about stock market trading.
In 2001, Birinyi launched the Laszlo Birinyi Sr. Distinguished Professorship in Hungarian Culture at the University of North Carolina in honor of his father. This $1 million endowment was “the first Hungarian culture professorship in the South, and it distinguishes Carolina as one of the few places in the United States where students may work with an expert in Hungarian studies.” 
- "Birinyi establishes first professorship in Hungarian culture". Carolina Connections. Retrieved 7 January 2016.
- "Laszlo Birinyi President Birinyi Associates, Inc" (PDF). AMC Houston. Retrieved 7 January 2016.
- "About Us". Birinyi. Retrieved 7 January 2016.
- WorldCat book entry
- "Executive Profile Laszlo Birinyi Jr". Bloomberg. Retrieved 7 January 2016.