StumbleUpon is the first web-discovery platform and personalized recommendation engine, co-founded by Garrett in 2002. In 2006 StumbleUpon relocated to San Francisco upon receiving its first round of funding from Silicon Valley angels. In 2007 StumbleUpon was listed in TIME's 50 Best Websites and in TIME’s 50 Must-Have iPad Apps in 2013. StumbleUpon was acquired by eBay for $75M in 2007 and later spun-out in 2009, becoming an independent company again. Garrett grew the company to over one hundred employees and over 25 million registered users as its founding CEO before stepping down in mid 2012 to work on other ventures. In August 2015, StumbleUpon was in financial debt and was re-acquired by Garrett Camp, who re-gained a majority share of the company after resetting all previous shareholders at $0/share. StumbleUpon continues to have functional web and mobile apps.

In 2009, Travis Kalanick joined Camp, who gives Camp "full credit for the idea" of Uber. Camp spent $800 hiring a private driver with friends and had been mulling over ways to decrease the cost of black car services ever since. He realized that sharing the cost with people could make it affordable, and his idea morphed into Uber. "Garrett is the guy who invented that shit," Kalanick said at an early Uber event in San Francisco. In mid-2009, the first prototype was built by Camp, and his friends, Oscar Salazar and Conrad Whelan, with Kalanick being brought on as a "mega advisor" to the company.

Uber launched in San Francisco in mid 2010 with just a few cars on the road and, in late 2010, raised $1.25M in angel funding. Uber’s motto is "Everyone’s Private Driver" and, in mid-2012, launched UberX and Uber SUV to offer customers low cost options and more vehicle choices. In late 2012, Uber launched UberTAXI, allowing taxi drivers to use the application with taxi-like fares for customers, and, in early 2013, CEO Kalanick announced that Uber will begin offering a ride-sharing Service, allowing community drivers to use the application.

Previously, Garrett invested in Prism Skylabs, a video analytics platform founded by Stephen Russell; SoundTracking, a music sharing application co-founded by Steve Jang of Schematic Labs; WillCall a live music ticket-buying application; and PSDept, a personal shopping application and BlackJet, an on-demand private aviation Service. Garrett was also a Series-A investor in Behance, prior to its acquisition by Adobe in 2012.

Garrett has been a speaker at conferences such as Wireless Influencers and South by Southwest, and was a judge and panel member at DEMO Mobile 2013 in San Francisco. Garrett participated in the World Economic Forum in New York, the PARC Forum Going Beyond Web 2.0 Series, and the Young Leaders of Silicon Valley hosted by VLAB, the San Francisco Bay Area chapter of the MIT Enterprise Forum.

In March 2014, Expa raised its first $50M from Investors to fund the design and development of new companies. Investors include Garrett Camp, Google board member Ram Shriram, Manjinder Singh, TPG founder David Bonderman, Virgin founder Sir richard Branson, HP CEO Meg Whitman, Li Ka-Shing & Solina Chau, First Round Capital, SherpaVentures, Booking.com Chairman Kees Koolen, SV Angel, Lerer Hippeau Ventures, WordPress founder Matt Mullenweg, Behance founder Scott Belsky, Undercurrent co-founder Josh Spear & author Tim Ferriss. In March 2016, Expa raised an additional $100m to fund the creation of new startups, and announced Expa Labs, an early-stage incubator program.

In 2015, he was the 283rd-richest person in the world and the third-richest Canadian, with an estimated wealth of US$5.3 billion according to Forbes. He has joined The Giving Pledge, a commitment to give away half of his wealth to charity. The Giving Pledge was created in 2010 by Warren Buffett and bill and Melinda Gates to encourage the world's richest people to "publicly dedicate the majority of their wealth to philanthropy" while they're still alive. In a personal blog post announcing his plans, Camp spoke of recent travels to Kenya, where he connected with people living without access to basic services like clean water, food and electricity.

According to Tech Crunch, as of June 2017, Camp had not been involved in Uber’s day-to-day operations for some time. However, according to a post he made on Medium the same month, he is still involved with the company.

Garrett has been interviewed by notable trade magazines, newspapers, radio shows and publications including Forbes, the Huffington Post, the Wall Street Journal, TechCrunch, BBC News, Inc. Magazine, PRWeek, Monocle’s Entrepreneurs and AllThingsD.