Cook graduated from Robertsdale High School in 1978. He earned a Bachelor of Science (B.S.) in industrial engineering from Auburn University in 1982, and his Master of Business Administration (MBA) from Duke University’s Fuqua School of Business in 1988.

After graduating from Auburn University, Cook spent 12 years in IBM’s personal computer business, ultimately serving as the director of North American fulfillment. It was during this time that Cook also earned his MBA from Duke University, becoming a Fuqua Scholar in 1988. Later, he served as the Chief Operating Officer of the computer reseller division of Intelligent Electronics. In 1997, he became the Vice President for Corporate Materials at Compaq for six months, but left the position after being hired by Steve Jobs.

Cook was misdiagnosed with multiple sclerosis in 1996, an incident he said made him “see the world in a different way”. He has since taken part in charity fundraising, such as cycle races to raise money for the disease. He later told the Auburn alumni magazine that his symptoms came from “lugging a lot of incredibly heavy luggage around”.

In 1998, Steve Jobs asked Cook to join Apple. In a commencement speech at Auburn University, Cook said he decided to join Apple after meeting Jobs:

In January 2007, Cook was promoted to lead operations and served as chief executive in 2009, while Jobs was away on a leave of absence for health related issues. In January 2011, Apple’s board of directors approved a third medical leave of absence requested by Jobs. During that time, Cook was responsible for most of Apple’s day-to-day operations, while Jobs made most major decisions.

During the 2008 election cycle, Cook donated to Barack Obama’s first White House election.

Cook has said that in 2009 he offered a portion of his liver to Jobs since they share a rare blood type. Cook said that Jobs responded by yelling, “I’ll never let you do that. I’ll never do that.”

After Jobs resigned as CEO and became chairman of the board, Cook was named the new chief executive officer of Apple Inc. on August 24, 2011. Six weeks later, on October 5, 2011, Jobs died due to complications from pancreatic cancer. Forbes contributor Robin Ferracone wrote in September 2011: “Jobs and Cook proceeded to forge a strong partnership, and rescued the company from its death spiral, which took it from $11 billion in revenue in 1995 down to less than $6 billion in 1998 … Under their leadership, the company went from its nadir to a remarkable $100 billion today”. In April 2012, Time included Cook on its annual “100 Most Influential People in the World” list.

While it had been reported in early 2011 that Cook was gay, at the time, and prior to his Oct. 2014 public statement, Cook chose to keep his personal life private. He did publicly support LGBT rights. In October 2014, the Alabama Academy of Honor inducted Cook, who spoke about his home state’s record of lesbian, gay, bisexual, and transgender rights. The Academy of Honor is the highest honor Alabama gives its citizens.

On October 29, 2012, Cook made major changes to the company’s executive team. Scott Forstall resigned as senior vice president of iOS, and became an advisor to Cook until he eventually departed from the company in 2013. John Browett, who was Senior VP of retail, was dismissed six months after he commenced at Apple, when he received 100,000 shares worth US$60 million. Forstall’s duties were divided among four other Apple executives: design SVP Jony Ive assumed leadership of Apple’s human interface team; Craig Federighi became the new head of iOS software engineering; services chief Eddy Cue became responsible for Maps and Siri; and Bob Mansfield, previously SVP of hardware engineering, became the head of a new technology group.

Alongside Google vice-president Vint Cerf and AT&T CEO Randall Stephenson, Cook attended a summit held by President Barack Obama, on August 8, 2013, in regard to government surveillance and the Internet in the wake of the Edward Snowden NSA incident.

As Apple Inc. CEO, Cook regularly begins sending emails at 4:30 a.m. and previously held Sunday-night staff meetings by telephone to prepare for the next week. Cook shared in May 2013 that his leadership focused on people, strategy, and execution; he explained, “If you get those three right the world is a great place.” Under Cook’s leadership, Apple has increased its donations to charity, and in 2013, he hired Lisa Jackson, formerly the head of the Environmental Protection Agency, to assist Apple with the development of its renewable energy activities.

Cook’s executive changes occurred after the third quarter of the fiscal year, when revenues and profits grew less than predicted. One commentator said that Forstall was forced to step down, as Cook “decided to lance the boil as internal politics and dissent reached a key pitch”. Since becoming CEO, Cook focused upon building a harmonious culture that meant “weeding out people with disagreeable personalities—people Jobs tolerated and even held close, like Forstall”; although, another journalist said that “Apple’s ability to innovate came from tension and disagreement.” On February 28, 2014, Cook made headlines when he challenged shareholders to “get out of the stock” if they didn’t share the company’s views on sustainability and climate change. In May 2016, Cook traveled to China to meet with government officials there after the closure of Apple’s online iTunes Store and Apple Books store by the Chinese government.

Cook is a fitness enthusiast and enjoys hiking, cycling, and going to the gym. He is known for being solitary, using an off-campus fitness center for privacy, and little is publicly shared about his personal life. He explained in October 2014 that he has sought to achieve a “basic level of privacy”.

In June 2014, Cook attended San Francisco’s gay pride parade along with a delegation of Apple staff. On October 30, Cook came out as gay in an editorial for Bloomberg Business saying “I’m proud to be gay, and I consider being gay among the greatest gifts God has given me.” He consulted with Anderson Cooper, who had publicly come out himself, on aspects of the statement, and cleared the timing to ensure it would not distract from business interests. Cook had been open about his sexuality “for years” and, while many people at the company were aware of his sexual orientation, he sought to focus on Apple’s products and customers rather than his personal life. He ended his op-ed writing “We pave the sunlit path toward justice together, brick by brick. This is my brick.” Cook became the first and only openly gay CEO on the Fortune 500 list. In September 2015, Cook clarified on The Late Show with Stephen Colbert, “Where I valued my privacy significantly, I felt that I was valuing it too far above what I could do for other people, so I wanted to tell everyone my truth.” In October 2019, he talked about the decision and remarked on how it was thanks to LGBTQ people who had fought for their rights before him that paved the way for his success; and that he needed to let younger generations know that—in a coding analogy—he saw being gay as a feature his life had to offer rather than any problem. He hoped his openness could help LGBTQ youth dealing with homelessness, and suicide hope that their situation could get better.

In 2015, Cook said he donated to Democratic senators Chuck Schumer and Patrick Leahy for their stances on eBook pricing and surveillance reform, respectively. During the same election cycle he hosted a fundraiser for Senator Rob Portman.

In 2016, some analysts compared Cook to former Microsoft CEO Steve Ballmer, claiming that innovation had died down since he replaced Jobs, similar to when Ballmer became Microsoft CEO in 2000. In December 2017, Cook was a speaker at the World Internet Conference in China.

Following the December 2015 terrorist attack in San Bernardino, California, in which 14 people were killed by Rizwan Farook and Tashfeen Malik, the Federal Bureau of Investigation solicited Apple to assist in “unlock[ing]” an iPhone 5C used by Farook. On February 16, 2016, in response to a request by the Department of Justice, a federal magistrate judge ordered Apple to create a custom iOS firmware version that would allow investigators to circumvent the phone’s security features. Cook responded in an open letter, wherein he denounced the government’s demands as constituting a “breach of privacy” with “chilling” consequences.

In the 2016 election, Cook raised funds for the presidential campaign of Hillary Clinton. At one point, Clinton’s campaign considered Cook as a candidate for vice-president.

In September 2017 at Bloomberg’s Global Business Forum, Cook defended the DACA immigration program. He expressed his dissatisfaction with the direction of Donald Trump’s administration, stating: “This is unacceptable. This is not who we are as a country. I am personally shocked that there is even a discussion of this.”

In 2018, at a privacy conference in Brussels, Cook expressed his opinions on the stockpiling of personal data by tech firms, suggesting that it amounted to surveillance and should make the public “very uncomfortable.”

Cook was appointed chairman of the advisory board for Tsinghua University’s economics school in October 2019. The length of his term will be 3 years.