The nearly 100 bills, he concluded, were bad for business and bad for human rights in general.
"These bills rationalize injustice," Cook said in the 550-word piece in the Washington Post. "They go against the very principles our nation was founded on, and they have the potential to undo decades of progress toward greater equality."
In a big departure from predecessor
In October, Cook made headlines around the world when he came out as gay in Bloomberg Businessweek, saying: "I consider being gay among the greatest gifts God has given me."
He has been thinking more about philanthropy as well, revealing in a Fortune interview last week that he would give away all of his wealth after paying for his nephew's college education.
Although Cook has been sharing his personal beliefs, he has also brought Apple into the conversation. In his weekend op-ed, he made clear that he was speaking "on behalf of Apple."
"Apple is open. Open to everyone, regardless of where they come from, what they look like, how they worship or who they love," he said.
Cook is forging an unusual path for a tech CEO. Longtime industry watchers note that it can be difficult for business executives to express their views without alienating customers, particularly those who want their iPhones without a side of social justice.
"A tech leader has to be careful how aggressive they get on social issues, given the fact that their job is more to run the company," said Tim Bajarin, president of Creative Strategies. "Having said that, I think it is a responsibility of a business leader, as it is for any public citizen, if they see something that they believe is wrong to speak up."
Cook wants others to speak up too. Acknowledging that such moves take courage, he said he was writing "in the hopes that many more will join this movement."
Historically, technology companies have shied away from such issues. During the 1980s and much of the 1990s, Bajarin said, tech leaders "were very cautious of making any kind of public statement outside of their comfort zones."
"The reason was, they were very reluctant to get on the radar of Washington," he said. "They did not want government intervention in the tech sector. They wanted to be left alone."
Apple itself was one of them.
"I never saw Steve Jobs take a position like this — he avoided this stuff like the plague," said Rob Enderle, principal analyst at Enderle Group. "It wasn't his thing. He felt the company was there to build products and that's what they're focused on and the rest was just noise."
Said Bajarin: "It's definitely a change from the Steve Jobs days. It's highly unlikely that Steve would have been this public about his position, but that would just be his nature — it wouldn't mean that Steve wouldn't have similar beliefs."
But with Cook taking a stand, others — particularly in liberal Silicon Valley — may very well follow suit.
Even before Cook's weekend op-ed, Salesforce.com founder Marc Benioff blasted the state of Indiana for signing into law a controversial bill that allows business owners to refuse to serve gays if doing so would violate their religious beliefs.
"We are forced to dramatically reduce our investment in IN based on our employee's & customer's outrage over the Religious Freedom Bill," Benioff tweeted Wednesday.
That was followed a few days later by an announcement from Indianapolis-based Angie's List that it would halt its campus expansion plans in Indiana to protest the law.
"Angie's List is open to all and discriminates against none and we are hugely disappointed in what this bill represents," said Bill Oesterle, chief executive of the business reviews site.
Yelp's CEO, Jeremy Stoppelman, also tweeted an open letter to states considering so-called discrimination laws.
"These laws set a terrible precedent that will likely harm the broader economic health of the states where they have been adopted, the businesses currently operating in those states and, most importantly, the consumers who could be victimized under these laws," Stoppelman wrote.
Cook has frequently turned to social media to share his views, recently tweeting about the Indiana bill, Selma, Abraham Lincoln and Georgia congressman
What Cook is doing "takes a lot of guts" because, from a business perspective, there is some risk to speaking out, Enderle said.
"It's not like people are going to buy more of your products if you're doing this," he said. "So not a lot of upside, a lot of potential downside — but it's still the right thing to do. So this is one of those things where the right thing and the economically prudent thing may be in conflict."