Sportswear manufacturer Nike, brewers Anheuser-Busch and cycle manufacturers Trek confirmed they were ending their relationships with Armstrong, while Oakley are reviewing their position after the doping scandal which has transcended sport.
The American was stripped of his seven Tour de France titles, won between 1999 and 2005, and banned from cycling for life by the United States Anti-Doping Agency in August after he chose not to contest charges, despite maintaining his innocence.
His reputation hit rock bottom a week ago when USADA published their report, including evidence from 11 of his former teammates.
The conclusion was that Armstrong engaged in "serial cheating" and his US Postal Service team ran "the most sophisticated, professionalised and successful doping programme that sport has ever seen".
Armstrong built a reputation around the world not just for his prowess on a bike but also as one of the giants of the charity sector for his work supporting cancer victims.
He set up Livestrong in 1997 following his own recovery from the disease, which made his subsequent sporting success such a compelling story, and the charity has raised nearly $500m (Dh1.8bn) to help people affected by cancer.
Explaining his decision to pass the chairmanship of the foundation to vice-chairman Jeff Garvey, Armstrong said in a statement: "In 1996, as my cancer treatment was drawing to an end, I created a foundation to serve people affected by cancer.
"It has been a great privilege to help grow it from a dream into an organisation that today has served 2.5 million people and helped spur a cultural shift in how the world views cancer survivors. This organisation, its mission and its supporters are incredibly dear to my heart.
"I have had the great honour of serving as this foundation's chairman for the last five years and its mission and success are my top priorities.
"Today, therefore, to spare the foundation any negative effects as a result of controversy surrounding my cycling career, I will conclude my chairmanship.
"My family and I have devoted our lives to the work of the foundation and that will not change. We plan to continue our service to the foundation and the cancer community."
Armstrong's resignation comes only a few days before a weekend of activities to celebrate Livestrong's 15th birthday in Austin, Texas.
Nike had stood by Armstrong last despite criticism but the sportswear giant today decided they could no longer do so, although they are not severing ties with Livestrong.
In a short statement, Nike said: "Due to the seemingly insurmountable evidence that Lance Armstrong participated in doping and misled Nike for more than a decade, it is with great sadness that we have terminated our contract with him.
"Nike does not condone the use of illegal performance-enhancing drugs in any manner. Nike plans to continue support of the Livestrong initiatives created to unite, inspire and empower people affected by cancer."
Trek announced in a statement they were also ending their relationship with Armstrong.
"Trek is disappointed by the findings and conclusions in the USADA report regarding Lance Armstrong," a statement read.
"Given the determinations of the report, Trek today is terminating our long-term relationship with Lance Armstrong.
"Trek will continue to support the Livestrong Foundation and its efforts to combat cancer."
Anheuser-Busch followed Nike in distancing themselves from Armstrong.
Paul Chibe, vice-president of US marketing, Anheuser-Busch, said in a statement: "We have decided not to renew our relationship with Lance Armstrong when our current contract expires at the end of 2012.
"We will continue to support the Livestrong Foundation and its cycling and running events."
Oakley, another of Armstrong's long-time commercial partners, are considering their position.
A statement from the sunglasses firm read: "We are reviewing the extensive report from the USADA, as well as our relationship with Lance, and will await final decision-making by the International Cycling Union."
The shock waves from the scandal are still reverberating through the sport. The five current riders who gave evidence against Armstrong and in the process implicated themselves all accepted six-month bans.
Cycling Australia yesterday sacked men's professional co-ordinator and national coach Matt White following his admission of doping while Johan Bruyneel has stepped down from his post as general manager of RadioShack Nissan Trek.
Bruyneel was team director of US Postal during Armstrong's time with the team but, unlike his former colleague, the Belgian is contesting USADA's charges.
Honorary president Hein Verbruggen and president Pat McQuaid have both come under pressure to step down from their posts with world cycling's governing body the UCI, while Armstrong could yet find himself facing charges of perjury.