Dimon, who runs the biggest U.S. bank, drew a contrast between Trump's moves and those of other elected officials who he said had not struck the right balance for the economy between regulation and free commerce.
He praised the Trump administration for insisting that "rules around cost-benefit analysis be properly applied" and for trying to give regulators "the proper authority to use common sense."
Using nearly half of the 46-page letter to promote his views on public policies, Dimon played to his roles as the public face of Wall Street and the chairman of the Business Roundtable, a CEO lobbying group.
Dimon said new federal tax law and "a more constructive regulatory environment" adopted since the 2016 presidential election give him hope that JPMorgan will be able to invest more of its excess capital to grow the bank and expand into new markets.
He emphasized JPMorgan's ability in the new climate to earn a return on tangible equity of 17 percent, two points higher than the target before corporate tax cuts were enacted and nearly four points greater than the company delivered in 2017.
Offering bank investors a view of the company stock, Dimon contended that it still made financial sense for JPMorgan to buy back shares "even at or above two times tangible book value" per share, which was $53.56 at year-end. JPMorgan shares closed at $110.99 on Wednesday.
To show that government regulation needs to be "smart," Dimon included a reprint of a 1992 newspaper essay by the late liberal U.S. senator and Democratic Party presidential candidate George McGovern, who recounted how he had learned late in life that regulations could crush businesses.
Dimon, 62, has said in the past that he was a Democrat, but in recent years he has avoided siding with a political party. He said in the letter that partisanship causes bad public policy.
He called for "improved merit-based immigration," particularly for those who get an advanced degree in the United States. "We need skilled individuals in America," he wrote.
He also said the U.S. should revisit the Trans-Pacific Partnership trade agreement, which Trump has rejected.
Interviewed later on Thursday morning on Yahoo Finance, Dimon said he and other CEOs had talked to Trump about trade policy a month ago.
"Obviously, we weren't very effective," Dimon said. ""We told him what we thought and it wasn't what he thought at the time."
Asked how Trump was doing as president, Dimon said he chose to address specific policy actions: "I am not going to assess a president after a year."
(Reporting by David Henry in New York; Editing by Bernadette Baum)
By David Henry