From 1983 to 1996, Roizen was co-founder and CEO of T/Maker Company, which made software for CP/M and MS-DOS computers, and later for the Apple Macintosh. Her brother, Peter Roizen was the other co-founder; he had graduated from the University of California, Berkeley, and had written the original software named "Table Maker" that had launched the company. From 1987 until 1994, Roizen also served on the board of directors of the Software Publishers Association and was its president from 1988 to 1990.
From 1996 to 1997, Roizen was Vice President of World Wide Developer Relations for Apple Computer. She also served on the board of Great Plains Software from 1997 until its acquisition by Microsoft in 2001.
Roizen entered the venture capital world in 1999, first as a Managing Director of SOFTBANK Venture Capital (which became Mobius Venture Capital), from 1999 to 2007, and then in 2012 she joined global investor Draper Fisher Jurvetson as a Venture Partner.
In June 2009, Roizen was elected to the Board of Directors of TiVo (NASDAQ:TIVO), and in September, 2012, she was elected to the board of DMGT (LSE:DMGT), the London-based global media and information company which owns the Daily Mail and Mail Online. At the time she was elected, she became the first female director in the company's 116 year history.
In 2010, Roizen was named a Lecturer and Entrepreneurship Educator at Stanford University, where she teaches the course 'Spirit of Entrepreneurship' in the MS&E (Engineering) department.
- Nancy Hellmich, USA Today (2008-01-06). "Businesswoman is dancing to a new, more healthful tune". Retrieved 2010-05-04.
- Forbes. "A big venture capitalist in Silicon Valley quits her day job to run a 'skinny' business.".
- Tam, Ruth (2015-01-30). "Artist behind Newsweek cover: it's not sexist, it depicts the ugliness of sexism". PBS NewsHour. Retrieved 2015-03-21.
- Heidi Roizen’s personal website
- Heidi Roizen on the Martha Stewart Show
- Harvard Business School Case: Heidi Roizen
- Forum for Women Entrepreneurs & Executives: Achievement Award 2008 Video
- Forum for Women Entrepreneurs & Executives Gives Roizen Achievement Award for 2008
- Interview on Fresh Dialogues Nov 2008 re. Skinny Songs
- Fresh Dialogues Interview Dec 2008 re. Tips for Entrepreneurs
- Entrepreneurial Heroes podcast interview with NCWIT
- Forbes.com - Untold Stories About Steve Jobs: Friends and Colleagues Share Their Memories
- Forbes.com - Heidi Roizen, Looking Outside Silicon Valley 'Cocoon,' Joins Daily Mail's Board