"These clients, the vast majority of whom are investing for long-term goals like retirement or a child's education, are the true owners of these companies," Fink said in his annual letter to S&P 500 CEOs.
"As a fiduciary, I write on their behalf to advocate governance practices that BlackRock believes will maximize long-term value creation for their investments."
When the long-term interests aren't considered, he added, "we do not hesitate to exercise our right to vote against incumbent directors or misaligned executive compensation."
Fink said assumptions held only a year ago have been capsized by Brexit, trouble in the Middle East and by President Donald Trump.
"At the root of many of these changes is a growing backlash against the impact globalization and technological change are having on many workers and communities," said Fink, a member of Trump's strategic and policy forum.
Still, he said: "I remain a firm believer that the overall benefits of globalization have been significant and that global companies play a leading role in driving growth and prosperity for all."