Breyer is currently on the boards of Etsy, Legendary Entertainment, Circle Financial, and 21st Century Fox where he is Chairman of the Compensation Committee and a member of the Nominating Committee. He is also a minority owner of the Boston Celtics.

Breyer was born in 1961 in New Haven, Connecticut, the son of Hungarian immigrants. His Father, John P. Breyer, was an Engineer and executive at International Data Group; his mother Eva was an executive at Honeywell. In 1983, Breyer received a B.S. with Distinction in Interdisciplinary Studies from Stanford University. He spent his junior year studying in Florence, Italy and is active in what is now Stanford's Breyer Center for Overseas Studies in Florence. He was drawn to Silicon Valley's Technology industry and during college he worked part-time for both Hewlett-Packard and Apple Inc. After college, he accepted a job as a management consultant for McKinsey & Company in New York for two years. In 1987, he earned a Master of Business Administration from Harvard University where he was named a Baker Scholar graduating in the top 5% of his class.

In 1987 he accepted a job with the venture capital firm Accel Partners in San Francisco and was mentored by founders Arthur Patterson and Jim Swartz. In 1990, he was named a partner and in 1995, he became a managing partner.

Breyer is married to shipping executive and philanthropist Angela Chao, the youngest sister of Elaine Chao and the widow of Bruce Wasserstein. He was previously married to his college sweetheart and impressionist Artist Susan Zaroff with whom he had three children, Emily, Daniel, and Theodore (Ted). They divorced in 2004.

In the past, Breyer has served on a number of public and private boards, including: Facebook from April, 2005 to June, 2013 where he was a Chairman of the Compensation Committee; Wal-Mart Stores, Inc., as the lead/presiding independent Director from 2001 until he resigned in June 2013; Marvel Entertainment as founding Chairman of the Strategic Planning Committee from 2006 until their acquisition by The Walt Disney Company in 2009; News Corporation from 2011 to 2013; Dell Inc., where he was the founding Chairman of the Strategic Planning and Finance Committee from 2009 until 2013; Brightcove, an online video platform which went public in 2012; and Model N as a founding investor and board member. Breyer is a member of the Council on Foreign Relations, Pacific Community Ventures, and TechNet. Jim is a Trustee of the Metropolitan Museum of Art, where his wife, Angela Chao, is also a Member of the Chairman's Council, and a Trustee of the San Francisco Museum of Modern Art.

In 2006, Breyer founded Breyer Capital, a global equity investor focused on providing capital to help catalyze high impact social and for-profit entrepreneurs. The fund focuses on emerging markets such as China, Brazil, and India. Breyer continues to manage the fund as CEO. Breyer Capital has participated in a number of Investments including Harvard's Experiment Fund, Brightcove, Marvel Entertainment and Legendary Pictures.

In August 2010, Fortune named Breyer one of the 10 smartest people in Technology, and the smartest investor in Technology. For three consecutive years, from 2011 to 2013, Forbes has ranked Jim Breyer number one on the Forbes Midas List of Tech's Top Investors. Breyer received the Silicon Valley Forum's Visionary Award in 2012. He was also named to the Vanity Fair New Establishment Hall of Fame in 2012. In 2014, Breyer was given a Lifetime Achievement Award by Venture Capital Journal.

In April 2013, a lobbying group called FWD.us (aimed at lobbying for immigration reform and improvements to education) was launched, with Jim Breyer listed as one of the founders.

In June 2014 IDG Capital announced the closing of IDG China Venture Capital Fund IV, a $586 million tech venture capital fund focused on making early-stage Technology, media and Telecom (TMT) Investments in China. IDG also announced the participation of Breyer Capital and stated Jim will play a leading strategic advisory role in the new fund.

In June 2016, the Wall Street Journal published a piece on what it one of the largest ever China-focused venture capital funds raised, $1 billion in capital commitments for the IDG Capital Fund III of Breyer and IDG Capital.

In December 2017, Breyer announced that he was looking into blockchain Technology. Just as China is ahead of the US in mobile payments and is investing heavily in artificial intelligence research, Chinese companies are not ignoring the immense potential of blockchain Technology. Breyer stated that one company that he was looking into was VeChain, as according to Breyer: "Last I checked, VeChain has a strong team and has already established some compelling partnerships with organizations like PwC. Ideally and eventually, Vechain will implement their Technology and help diminish numerous supply chain inefficiencies. If Vechain can execute, they could be a leader in item validation, and capture a meaningful portion of the growing cross border e-commerce market. The Chinese blockchain industry, from small companies with tokens to major enterprises, is flourishing and should not be ignored. I took a bold bet on China over a decade ago and remain as convinced as ever that Chinese innovation will resume at a rapid and competitive pace."