During the packed outdoor concert on a rain-soaked night in Miami, Lopez put on a dramatic performance where she interspersed songs with huge images of Clinton and First Lady Michelle Obama during her Democratic convention speech.
The event was meant to fire up Hispanic voters and drive turnout in a must-win state for Clinton's rival, Republican candidate Donald Trump, in the election's final days.
During the show, Clinton urged supporters not to let Trump get away with 'stoking fear' and 'insulting one group of Americans after another.'
Playing off Lopez's hit Let's Get Loud, a staple at Clinton rallies, she also urged Floridians to 'get loud at the voting booth.'
'Are you ready for your voices to be heard?' J-Lo sang while donning a sequin American flag outfit as she opened the show with the song Let's Get Loud.
She added: 'We're gonna change things.'
'When they go high, we go low,' the First Lady intoned, while J-Lo performed with her 10 back-up dancers.
'Now fellows I love you but I need to talk to the ladies right quick,' Lopez said.
'Now I'm a hard working woman, do you know that? I work hard for the money… You know what, you gotta respect that,' she said – without having to mention Clinton's all-out appeal to women voters, or backing of 'equal pay' legislation.