Billionaire Ken Griffin is relocating his big hedge-fund firm Citadel from Chicago to Miami, the third major employer to announce the move of a corporate headquarters from Illinois in the past two months.

In a letter to employees Thursday that was viewed by The Wall Street Journal, Mr. Griffin said he had personally moved to Florida and that his market-making business, Citadel Securities, would also transfer. He wrote he views Florida as a better corporate environment and though he didn’t specifically cite crime as a factor, company officials said it was a consideration.

Mr. Griffin is the wealthiest resident of Illinois, so his departure will hurt state tax collections on both the individual and corporate side. Mr. Griffin has an estimated worth of $28.9 billion and is among the world’s top 50 wealthiest, according to the Bloomberg Billionaires Index.

“Chicago will continue to be important to the future of Citadel, as many of our colleagues have deep ties to Illinois,” Mr. Griffin wrote. “Over the past year, however, many of our Chicago teams have asked to relocate to Miami, New York and our other offices around the world.” The Citadel move is expected to be a multiyear process. There are currently about 1,000 employees in Chicago and many are expected to remain.

Citadel is one of the most successful hedge-fund firms, managing $51 billion in assets and consistently outpacing competitors via its multistrategy funds after surviving steep losses in the 2008 financial crisis.

Mr. Griffin and Illinois Gov. J.B. Pritzker, an heir to the Hyatt H, -2.48%  hotel fortune and the brother of former U.S. Commerce Secretary Penny Pritzker, have had a running feud in recent years, lately over rising violence in Chicago. Mr. Griffin has donated $50 million ahead of Tuesday’s Illinois primary to the campaign of Richard Irvin, a suburban Chicago mayor running for the Republican nomination for governor. He is also a major donor to efforts nationwide to try to help the GOP gain control of Congress in November.

Data from the Chicago Police Department show that through June 19, murders are down 11% when compared with the same period a year earlier, while thefts are up 65%, motor vehicle thefts are up 40% and burglaries are up 31%.

Caterpillar Inc said earlier this month it was moving from its longtime Illinois base to Texas. Manufacturers have increasingly turned to the Southwest as a destination for new factories, drawn by available space, appealing tax policies and an expanding technology workforce. In May, Boeing Co BA, -1.81% said it was moving its headquarters from Chicago to Arlington, Va., in order to be closer to top federal officials.

Citadel Securities has had a presence in Florida since March 2020, when employees started working from a high-end hotel there at the start of the Covid-19 pandemic. In his note to employees, Mr. Griffin said the new headquarters would be on Brickell Bay, “in the heart of Miami’s booming financial district.”

D1 Capital Partners, Elliott Management Corp. and Melvin Capital Management are also among the firms that now have a presence in Florida, making it a new satellite of New York and Connecticut for the hedge-fund industry.

An expanded version of this story appears on WSJ.com.