The former president went to New Hampshire in support of his wife, the former secretary of state, senator and first lady who leads polls for the Democratic nomination for the presidency.
Clinton addressed a rally at a community college in the city of Nashua, paying tribute to Hillary's determination to make America a fairer, safer country for the poor and struggling middle classes.
He made no direct reference to Donald Trump, the brash billionaire dominating the Republican race for the White House who recently stepped up personal attacks on both Clintons.
New Hampshire is host to the nation's first presidential primary on February 9.
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Bill Clinton said Hillary's skill set "offers the best chance to have the most rapid movement to more broadly shared prosperity."
"In an uncertain world, where borders look more like nets than walls, and no one is in total control, she understands what it takes to keep our country as safe as possible," he said, dressed in an open-necked shirt, dark pullover and blazer, wearing a Hillary pin on his lapel.
When they met at Yale Law School 45 years ago, he said he thought she was "the most amazing person" who could have secured any job in life but who wanted only to provide legal aid to the poor.
"Everything she touched, she made better," he said, paying tribute to her long career and calling her a "change maker."
Trump, the real estate tycoon who has led Republican polls for months, recently blasted Bill Clinton's "terrible record" with women -- an apparent allusion to his past alleged marital infidelities.
Clinton said many leaders in corporate America were
prioritising their short-term stock price over their workers and their communities.
"We can't forget the damage caused by trickle-down economics and right-wing ideologues who believe in weakening government oversight, massive tax cuts for the rich, ripping away the safety net, and breaking the backs of unions," she said.
Sending a clear message to every board room and executive suite, Clinton warned that they would be held accountable if they cheat employees, exploit customers, pollute the environment or rip off the taxpayers.
"To discourage bad behaviour, we'll make companies pay for what are called inversions under the tax code, which means they pretend to sell themselves to a company overseas. And then they pretend to move their headquarters overseas," Clinton said.
"I call it a perversion, but under the tax code it's called an inversion. We will make you pay for that with a new exit tax," she said.