In 1973, he and some former classmates founded Kinpo Electronics (zh), a manufacturer of handheld calculators. As President of the company he built it into the largest contract manufacturer of calculators. In the late 1980s, he became convinced that notebook computers would be the next big product. He left Kinpo and founded Quanta Computer in 1988. He set up Quanta Computer with the help of a colleague, C. C. Leung, with capital of less than US$900,000. It had a turnover of NT$777 billion in 2007, US$23.7 billion.

Quanta Computer's flexibility has become a by-word for Taiwanese competence in the high-tech world, and Lam is seen as the founder of the engineering / design / Manufacturing model, which launched Taiwan's High Tech Industry. Lam's visionary view of the PC notebook world can be seen as the driving force behind the success and prolific growth of the notebook in the late 1990s.

In November 2002, Barry Lam announced that he would fund a new College of Electrical Engineering and Computer Science at his alma mater National Taiwan University. It opened in July 2004, and is known as the Barry Lam Hall. It houses the Barry Lam Art Gallery in its basement.

In 2005, Barry Lam and Quanta joined forces with MIT on Project T-Party, a five-year initiative that will create the next generation of platforms for computing and communication. Combining the huge brainpower of MIT with the practical skills of Quanta, the project aims to create new interfaces and explore new ways of managing and accessing information. Lam commented on the project, "We are very pleased to team up with the renowned research institution, MIT, to embark on a new IT trendsetting endeavor. Combining the exceptional research resources of MIT with the world-leading innovative design and Manufacturing engine of Quanta, we are excited about the prospects of bringing brand-new products and services to the world that will improve all of our lives and cultures."

Barry Lam is recognized as one of the front-runners of the high-tech field, which some attribute to a combination of engineering talent, innovative thinking and entrepreneurial skills. He has built Quanta into one of the biggest high-tech companies worldwide. In 2006, Fortune Magazine recognised Quanta as one of the Fortune Global 500 Companies, and in 2007, Forbes placed Quanta 15th in its ranking of the world's most admired computer companies, the highest ranking of a Taiwanese company. Quanta designs and manufactures for clients such as Apple Inc., Compaq, Dell, Gateway, BlackBerry Ltd., Hewlett-Packard, Alienware, Cisco Systems, Fujitsu, Gericom, Lenovo, LG, Maxdata, MPC, Sharp Corporation, Siemens, Sony, Sun Microsystems, and Toshiba. It is the largest manufacturer of PC notebooks worldwide and it has also Diversified into servers, storage, and liquid-crystal display terminals.

Barry Lam decided that Quanta would be the original design manufacturer (ODM) for the OLPC XO-1 by the One Laptop per Child project. Quanta took orders for one million laptops as of 2007-02-15. The OLPC project was also part of Quanta's Blue Ocean Strategy, entering new market segments which are uncontested in terms of competition.

In May 2008, celebrating its 20th anniversary, Quanta was named as Taiwan's second largest private Manufacturing enterprise. It had an annual turnover in 2007 of NT$777 billion, posting a 45% revenue growth. In 2001, a tough year for most computer companies, Lam led Quanta to world dominance as it became the largest notebook manufacturer worldwide and increased production by 50%. In 2002, Quanta moved production to mainland China where it established a large Manufacturing base with the aim of reducing costs.

“If users paid fees [when using a public computer], the OLPC could become even cheaper. This is because when using your device, you would be actually using the resources of the public computer, so that the OLPC would not have to be equipped with computer functions at all. For instance, sending video and audio files, downloading games – depending on which game I want to play or which TV channel I want to watch – I can get them from a multimedia public computer. It could evolve into only paying for what you use, and not having to pay for what you don't use. The Future, I believe, will be the age of OLPCs and public computers.”