Greiner was born in London in 1967. Her father came to England as a refugee from Hungary, and met his wife, Helen's mother, at the University of London. When Helen was 5, her family moved to Southampton, New York, USA.
At the age of ten Greiner went to see the popular film Star Wars. She has said she was inspired to work with robots by R2D2 in the film .
Greiner graduated from the Massachusetts Institute of Technology in 1989, and earned her Master's there (SM) in 1990.
In 1990, along with Rodney Brooks and Colin Angle, Greiner co-founded iRobot, a robotics company headquartered in Bedford, Massachusetts, which delivers robots into the consumer market. She co-designed the first version of the iRobot Roomba.
Greiner served as President of iRobot (NASDAQ: IRBT) until 2004 and Chairman until 2008. During her tenure, iRobot released the Roomba, the PackBot and SUGV military robots. She built a culture of practical innovation and delivery that led to the deployment of 6,000 PackBots with the United States armed forces. In addition, Greiner headed up iRobot’s financing projects, raising $35M in venture capital for a $75M initial public offering.
She has worked at NASA's Jet Propulsion Laboratory and the MIT Artificial Intelligence Laboratory.
Greiner is currently CTO of CyPhy Works, home to the Persistent Aerial Reconnaissance and Communications (PARC) and Pocket Flyer multi-rotor drones. She also serves on Open Source Robotics Foundation (OSRF).
In 2014, Greiner was named a Presidential Ambassador for Global Leadership (PAGE) by US President, Barack Obama and US Secretary of Commerce, Penny Pritzker.
She received the 2008 Anita Borg Institute Women of Vision Award for Innovation for her work at iRobot. She has also been honored as one of Technology Review Magazine's TR100 "Innovators for the Next Century."
In 2007, Greiner was inducted into the Women in Technology International Hall of Fame.
In 2006, she received the Pioneer Award from the Association for Unmanned Vehicle Systems International(AUVSI).
She received the DEMO God Award at the DEMO Conference.
In 2005, she was named "Entrepreneur of the Year" by Good Housekeeping and she was named by the Kennedy School at Harvard in conjunction with the U.S. News & World Report as one of "America's Best Leaders."
In 2003, Greiner and iRobot co-founder Colin Angle were named Ernst and Young New England Entrepreneurs of the Year.
In 2003, Greiner was named one of the “Top Ten Innovators” by Fortune Magazine.
In 2000, Greiner was also listed as one of the Global Leader of Tomorrow by the World Economic Forum.