Born in the Chicago area, he graduated from Niles West High School in 1981 and then graduated with bachelor's degrees in electrical engineering and computer science from Northwestern University in 1985 and an MBA from Stanford University in 1989.
Kremen launched the software firm Los Altos Technology and headed the company until late 1992.
In 1993, Kremen founded Electric Classifieds, Inc. the first company to bring classified advertising to the Internet. Funded by private investors in November 1994, he launched the online personals service Match.com in April 1995. After troubles with venture capitalists over his insistence that the company serve profitable alternative market segments including the LGBT market, he left Match.com in March 1996, remaining on the board of Electric Classifieds. Over Kremen's objections, Match.com was sold to Cendant Corporation for $7 million in 1998 and sold by Cendant to Ticketmaster a year and a half later for $50 million.
From 1995 to 1996, Kremen founded and served as president of NetAngels.com, Inc., an Internet profiling and personalization company that suggested web sites to users. He left when NetAngels merged with Boston personalization software firm Firefly Network, Inc. in 1997, and Firefly was sold to Microsoft in 1998 in a reported $40 million deal.
In 1999, he was listed as an equity-holding officer or director of Brightcube, Inc.
Kremen is credited as a primary inventor on a 1995-filed patent for dynamic web pages, US patent number 5,706,434, which he later sold for over $1,250,000. Additionally, Kremen holds two other patents in financial-related systems management: US patent number 7,698,219 and US patent number 7,890,436
Kremen resides in the San Francisco Bay Area. He is the founder of residential solar financing start-up Clean Power Finance, Inc., which raised $6.9 million from investors in January 2010, $25 million from Kleiner Perkins, $75 million from Google  in September 2011, and $62 million from other investors.
He was also founder and chairman of Sociogramics, a financial services company that focuses on bringing credit to the underbanked, having raised seed capital from Tugboat Ventures, Harmony Venture Partners, Trinity Ventures, Greylock Partners, Claremont Creek Ventures, and QED Investors.
Since 1993, Kremen has been a private and angel Investor in over 50 companies (individually or through venture capital funds), of which several have gone public or had liquidity events. Kremen is the founding investor and a board member of CrowdFlower and WaterSmart Software and CapGain Solutions. He is an elected board member and president of the Purissima Hills Water District as well as involved with local non-profit organizations. He is also a co-founder of Menlo Incubator, which is an early-stage startup program that focuses heavily on mentorship.
Kremen was appointed to the Proposition 39 Citizens Oversight Board by California State Controller John Chiang in January 2014. On February 24, 2014, Identive Group (NASD: INVE) appointed him a member of the Board of Directors.
In August 2014, Kremen announced his candidacy for the Santa Clara Valley Water District Board of Directors on a website GaryForWater.Com. He beat his opponent, the incumbent in the November 4th, 2014 election. On January 13, 2015, the Board elected him as the 2015 Board Chair.
Kremen took the matter to the courts where he struggled to make a case, on limited resources, against Cohen's multi-million dollar pornography empire.
In the meantime, however, Cohen had profited vastly through the property and Kremen tried to wrest back some of these profits through further court action. He was awarded a judgment of $65 million against Cohen, but Cohen fled to Mexico and moved the money offshore. Kremen did successfully obtain Cohen's Rancho Santa Fe mansion, where Kremen relocated to after the court case resolved. Kremen also successfully litigated against Network Solutions.
- Gary Kremen's personal website
- Gary Kremen's current position as CEO of Clean Power Finance
- An archive of articles on the Sex.com case
- Wired article on Match.Com and Gary Kremen
- 1997 Forbes Article on Gary Kremen
- "Sex.com" news article on the court case - The Guardian Newspaper'
- News article on Kremen's sale
- DNJournal: The Continuing Saga of Gary Kremen and Sex.com
- The Prisoner of Sex.Com
- The Sex.Com Chronicles, A White-Hat Lawyer's Journey to the Dark Side of the Internet
- OPW - Interview with Gary Kremen, January 2012
- Showley, Roger M. Web site founder adjusts to life in Rancho Santa Fe. SignOnSanDiego.com, 2004-05-24. Retrieved on 2007-08-08.
- Brightcube Inc, 10SB12G, On 7/13/99 SECInfo.com, 1999-07-13. Retrieved on 2007-08-08.
- Angwin, Julia. "Love's labor lost: Online matchmaker still seeks love, money." San Francisco Chronicle, via sfgate.com, 1998-02-12. Retrieved on 2007-08-13.
- O'Brien, Chris. "The Prisoner of Sex.com." Wired, via wired.com, August 2003. Retrieved on 2007-08-13.
- Ginsberg, Steve. "Perfect match: Wheeler-dealer, investment bank aim cash at 'Net." San Francisco Business Times, via bizjournals.com, 1997-01-19. Retrieved on 2007-08-13.
- Luening, Erich. "Microsoft to buy Firefly." CNET News.com, 1998-04-09. Retrieved on 2007-08-13.
- United States Patent 5706434 United States Patent and Trademark Office, 1998-01-06. Retrieved on 2007-08-08.
- United States Patent number 7,698,219 Issued April 13, 2010: Methods, systems and agreements for increasing the likelihood of repayments under a financing agreement for renewable energy equipment.
- United States Patent number 7,890,436 Issued February 15, 2011: Billing and payment methods and systems enabling consumer premises equipment.
- Rivlin, Gary. In Silicon Valley, Millionaires Who Don’t Feel Rich New York Times, 2007-08-05. Retrieved on 2007-08-08.
-  Greentech Media, Retrieved on 2009-01-05
-  Google invests $75M into Clean Power Finance solar fund
-  Google Invests $75 Million in Home Solar Venture
- Joined the Board of Directors of Identiv (NASD: INVE) http://finance.yahoo.com/news/gary-kremen-joins-board-identiv-140000528.html today
- Kozinski, Alex. United States Court of Appeals for the Ninth Circuit, No. 01-15899 D.C. No. CV-98-20718-JW Opinion Findlaw, 2003-07-25. Retrieved on 2007-08-08.
- McCarthy, Kieren. Sex.com thief arrested The Register, 2005-10-28. Retrieved on 2007-08-08.
- Sex.com Sold for $12M Foxnews.com, 2006-01-24. Retrieved on 2007-08-08.
- Jackson, Ron. Be Careful what You Wish For: The Continuing Saga of Gary Kremen and Sex.com DNJournal.com, March, 2006. Retrieved on 2007-08-08.
- Jackson, Ron. Diamond.com Shines Bright After Selling for $7.5 Million in One of the Biggest Domain Deals Ever Reported DNJournal.com, 2006-05-23. Retrieved on 2007-08-08.