They delivered moving remarks and shared their favorite (often humorous) stories about the senator, Vietnam veteran, former prisoner of war and 2008 Republican presidential candidate whose death from brain cancer has affected people across the country.
Here are moments from the service that summed up what McCain meant to his friends, and to the nation.
'I'm a Democrat. And I love John McCain'
Biden spoke about his more than four decades of friendship with McCain, and lamented how rare a bond like theirs, which transcended political partisanship, has become on Capitol Hill today.
"I'm Joe Biden. I'm a Democrat. And I love John McCain," Biden said of his longtime Senate colleague. He compared their disagreements over the years to fights between brothers and said McCain could always look past a specific political argument.
"It wasn’t about politics with John. You could disagree on substance," Biden said. "It was about the underlying values that animated everything John did."
'John came from another age'
Biden said it was more than his respect for this political opponent that made McCain special, Biden said. It was the "McCain code" that defined him.
"Things have changed so much in America, they look at him as if John came from another age because he lived by a different code, an ancient, antiquated code where honor, courage, character, integrity, duty mattered," Biden said.
"I was thinking this week about why John’s death hit the country so hard," Biden said. "I think it’s because they knew that John believed so deeply and so passionately in the soul of America."
'He cared about the substance of my heart'
Arizona Cardinals' wide receiver Larry Fitzgerald said people often wondered, and he sometimes asked himself, how he could have become friends with someone who, on the surface, was so different from himself.
"I'm black, he was white," Fitzgerald said. "I'm young. He wasn't so young. He lived with physical limitations brought on by war. I'm a professional athlete. He ran for president. I run out of bounds.
"He was the epitome of toughness and I do everything I can to avoid contact. I have flowing locks, and well, he didn't. How does this unlikely pair become friends? I've asked myself the same question. You know what the answer is? That's just who he is."
"What made Sen. McCain so special was that he cared about the substance of my heart" more than all their differences, he said.
'Arizona fell in love with John McCain'
From his birth on a Navy base in Panama, through a childhood that included about 20 schools and a more than 20-year Navy career, McCain lived a fairly nomadic life until he moved to Arizona.
Former Arizona Attorney General Grant Woods said McCain fell in love with the people of Arizona, the diversity of the community and the state's natural beauty.
"If John McCain fell in love with Arizona, Arizona fell in love with John McCain," said former Arizona Attorney General Grant Woods.
'He understood all of us'
McCain understood and appreciated Arizona's large immigrant community, said Tommy Espinoza, president of the Raza Development Fund Inc., a non-profit which specializes in providing loans in poor Latino communities.
"He did understand us. He understood all of us, whether it was white, black, brown or Asian. To him, it didn't make any difference. What he knew is that we all make America great. We all make America great," Espinoza said.
Contributing: Dan Nowicki, Ronald J. Hansen and Yvonne Wingett Sanchez, Arizona Republic