His death Monday was confirmed by Kleiner Perkins Caufield Byers, a venture capital firm that often called upon Campbell to help mold entrepreneurs as they tried to manage the rapid growth often triggered by their innovations. Campbell died after a long battle with cancer, according to the firm, which was speaking on behalf of his family.
After working in marketing and sales at Apple during the 1980s, Campbell joined the company's board in 1997, shortly after Jobs returned as the company's CEO.
At the time, Apple was flirting with bankruptcy. Campbell frequently served as Jobs' sounding board during one of the most resounding corporate turnarounds in US history as Apple first redesigned its Mac computer line and then rolled out the iPod, iPhone and iPad to emerge as the world's most valuable company. Campbell ended his 17-year stint on Apple's board in 2014.
Campbell "believed in Apple when few people did and his contributions to our company, through good times and bad, cannot be overstated," Apple said in a Monday statement.
While working with Apple, Campbell played a behind-the-scenes role in Google's success, too. Prompted by Kleiner Perkins, Campbell worked with former Google CEO Eric Schmidt and company co-founders Larry Page and Sergey Brin to help them work out their early differences and eventually forge one of the most successful partnerships in corporate America.
Alphabet, Google's corporate parent, is now the world's second most valuable company, ranking only behind Apple.
In a Facebook post, Schmidt credited Campbell for helping to build Google's culture and hailed his contributions to the company as "incalculable."
"We started with him as an external coach but he quickly became the internal management expert," Schmidt wrote.
Campbell stopped consulting with Google in 2010, citing the conflicts of interest that faced him as an Apple board member. Google makes the Android operating system that powers most of the products competing against Apple's trendsetting iPhone and iPad.
Campbell's background gave little inkling he would become one of Silicon Valley's most influential figures.
Before joining Apple, Campbell spent six seasons as the head coach of Columbia University's football team. He compiled a 12-41-1 record at Columbia, a .231 winning percentage that was more than double that of his three successors.
As a student at Columbia, Campbell was the captain and an offensive guard on the football team that went 6-3 in 1961, including a 6-1 record in the Ivy League that earned the university a share of the conference title with Harvard. It's still the only time that Columbia's football team won the Ivy League.
Even after he left football, Campbell remained known as "Coach" in Silicon Valley. He also owned an interest in a sports bar in Palo Alto, California, where he regularly met with friends and colleagues at a table with a brass plaque inscribed "Coach's Corner."
Before becoming a mentor to other companies, Campbell was CEO of software maker Intuit Inc. from 1994 to 1998. He later served as that company's chairman until stepping down earlier this year.