His daughter, Catherine Florio Pipas, confirmed his death but did not cite a cause.

Mr. Florio grew up in Brooklyn, the son of an Italian American shipyard painter, and brought to the political arena the same intensity that he had shown as an amateur boxer. He had once entered the ring with an opponent who broke Mr. Florio’s left cheekbone, permanently crushing that side of his face.

“I don’t start fights,” Mr. Florio told the New York Times of his later bouts in politics, “but I don’t walk away from them.”

Mr. Florio spent decades in public office, serving in the New Jersey General Assembly for four years before winning his Camden-based U.S. House seat in 1974. He became, in the description of the Almanac of American Politics, “one of the fathers of the Superfund,” the multibillion-dollar federal program established in 1980 to clean up hazardous waste sites across the United States.

He weathered two unsuccessful bids for governor before winning the office in 1989. At the time, amid a national recession, New Jersey faced a budget shortfall that threatened to reach $600 million. During his campaign, Mr. Florio was imprecise on how he would address the deficit. But he did declare, according to the Bergen Record: “You can write this statement down: ‘Florio feels there is no need for new taxes.’ ” He defeated Republican Jim Courter in a landslide, 61 percent to 37 percent.

But within months of taking office, Mr. Florio concluded that he had no option but to raise income and sales taxes, for a total increase reaching $2.8 billion. It was “the largest state tax increase in American history at that time,” said Rutgers University political scientist Ross K. Baker, a “spectacularly large amount of money” that proved particularly “irksome” to voters because it included taxes on household items such as toilet paper.

Protesters hurled rolls of toilet tissue at the New Jersey State House, where Republicans soon claimed majorities in both chambers. Mr. Florio’s popularity plummeted. An editorial cartoon described in a campaign dispatch by the Times depicted Saddam Hussein gazing at himself and asking, “Magic mirror on the wall, who’s the most hated and feared leader of them all?” In the next panel, the Iraqi dictator angrily shouts, “Who the *@#!!?* is Jim Florio?!””

Announcing his candidacy for reelection in 1993, Mr. Florio remarked that “we made difficult decisions, many of which I hated to do. But the alternatives were worse, including the most expensive alternative of all — the cost of doing nothing.” Promising to reduce state taxes, his Republican opponent, Christine Todd Whitman, won by 26,000 votes, a margin of 1 percent.

In a statement after Mr. Florio’s death, New Jersey’s current governor, Phil Murphy (D), described him as “a leader who cared more about the future of New Jersey than his own political fortunes.”

Baker remarked that critics who reduce Mr. Florio’s political career to the ire provoked by his tax increase overlook “a large and important part of a long and distinguished political career.” Mr. Florio worked to lower auto insurance rates and established a record on environmental protection, especially where the New Jersey shore and the state’s Pinelands were concerned, that Baker described as “outstanding.”

But perhaps his chief legacy, Baker said, was the gun-control law enacted in 1990, during Mr. Florio’s early months in office. Mr. Florio later defended the measure, which banned a wide rage of assault weapons, from repeal amid an attack by the NRA. The ban remains in place today.

James Joseph Florio was born in Brooklyn on Aug. 29, 1937. His mother was a homemaker. After his father lost his shipyard job following World War II, the family struggled financially.

Mr. Florio left high school to join the Navy in 1955 and later earned a high school equivalency degree. He remained in the Navy Reserve until 1975, reaching the rank of lieutenant commander. He received a bachelor’s degree in social studies from Trenton State College in 1962 and a law degree from Rutgers in 1967. During law school, he worked after hours as a janitor to support his children.

In the early years of his career, Mr. Florio practiced law in Camden, which became his political base. He won his seat in the General Assembly in 1969 and unsuccessfully challenged U.S. Rep. John E. Hunt in 1972 before unseating the Republican incumbent as a member of the Watergate class of 1974. In addition to his work on the Superfund legislation, Mr. Florio spearheaded efforts to clear schools of asbestos.

Baker described Mr. Florio as constitutionally “an executive type” more than a congressional one. He failed in a bid to unseat incumbent Gov. Brendan T. Byrne in the 1977 Democratic primary. Four years later, Mr. Florio tried again for the governor’s office and lost so narrowly to Republican Thomas H. Kean that a recount dragged on for weeks. Kean held the office until Mr. Florio succeeded him in 1990.

In 2000, Mr. Florio sought a return to politics and ran for the U.S. Senate seat vacated by Democrat Frank Lautenberg. He lost a bruising and expensive primary race to investment banker Jon S. Corzine, who prevailed and remained in the Senate until taking office as New Jersey governor in 2006.

Mr. Florio’s marriage to Maryanne Spaeth ended in divorce. In 1988, he married Lucinda Coleman.

Besides his wife, of Morristown, N.J., survivors include three children from his first marriage, Christopher Florio of Ipswich, Mass., Gregory Florio of Haddon Heights, N.J., and Catherine Florio Pipas of Lebanon, N.H.; a stepson, Mark Rowe of Mount Laurel, N.J.; a brother; 10 grandchildren; and two great-grandchildren.

After his political career, Mr. Florio practiced law in Cherry Hill, N.J. He wrote a memoir, “Standing on Principle: Lessons Learned in Public Life” (2018).

Speaking to the Philadelphia Inquirer that year, he said he was “at peace” with his defeat as governor. Voters may have been angry about the tax increase, but his gun law was “still the toughest assault weapon ban in the country.”