President Donald Trump, Vice President JD Vance and several cabinet members were scheduled to pay tribute to the charismatic Kirk 11 days after he was assassinated during a campus event in Utah.
The memorial, organised by Kirk's conservative youth advocacy organisation Turning Point USA, had the feel of a religious revival mixed with a "Make America Great Again" political rally.
Stephen Miller, the powerful White House adviser, vowed to use Kirk's death as a galvanising force to finish the work he began.
"We will carry Charlie and Erika in our heart every single day, and fight that much harder because of what you did to us," Miller said.
"You have no idea the dragon you have awakened. You have no idea how determined we will be to save this civilisation, to save the West, to save the republic."
Christian rock music blared through loudspeakers and pictures of Kirk were set on easels throughout the walkways of State Farm Stadium in Glendale, Arizona. The arena, which normally has a capacity of 63,000, appeared completely full. Crowds of people, many wearing MAGA merchandise, had arrived before dawn to secure seats inside the stadium, where they encountered metal detectors amid tight security.
Trump, who was set to close the event with his remarks, has credited Kirk with mobilising young voters behind his campaign last year. Civil rights groups criticised Kirk for rhetoric they described as racist, anti-immigrant, transphobic and misogynistic, while his backers say he was a defender of conservative values and a champion of free speech.
Other speakers included Secretary of State Marco Rubio and Secretary of Defence Pete Hegseth, more evidence of Kirk's political influence.
Kirk, 31, was killed with a single bullet as he answered an audience member's question at a campus event in Utah organised by Turning Point. A 22-year-old technical college student has been charged with Kirk's murder, and investigators say he told his romantic partner in text messages that he had killed Kirk because he had "enough of his hate."
Kirk had two young children. His wife, Erika Kirk, was elected the new chief executive of Turning Point in the wake of his death and delivered an emotional address on Sunday.
"My marriage with Charlie was the best thing that's ever happened to me," she said.
Kirk's death has raised fears about the growing frequency of US political violence across the ideological spectrum, while also deepening partisan divides.
Trump has cited the murder in escalating his calls for a crackdown on his political opponents, including left-wing organisations that he has blamed for the shooting even though authorities have said the gunman acted alone.
During her remarks, Tulsi Gabbard, the US director of national intelligence, tied Kirk's killing to what she described as a historical pattern in which "political fanatics" eventually turn to violence to defend their ideals.
"They kill and terrorise their opponents, hoping to silence them," she said.
"But in this evil that we have experienced - that Charlie faced - their flawed ideology is exposed, because by trying to silence Charlie, his voice is now louder than ever."
Regina Starr, 59, a semi-retired volunteer who helps care for the elderly, said Kirk's defining trait was not his politics or his role in founding Turning Point USA - it was his unapologetic Christianity.
"He didn't try to shove it down people's throats," she said. "He was just open. He shared the love of Jesus like he breathed it - naturally, fearlessly. And that made him a target."
