The pair spoke in front of media and Trump supporters at a news conference at 11 a.m. Saturday. The formal announcement was supposed to take place 24 hours earlier, but was postponed due to the Nice, France, terror attack that killed dozens of people on Thursday night. Trump then preempted his own press conference by announcing his choice Friday on Twitter.
Trump offered sympathies to the victims in France and commented on the attempted coup in Turkey and his opponent, Democrat Hillary Clinton, before offering words of praise for Pence.
"Indiana Gov. Mike Pence is my first choice," Trump said amid reports he was reconsidering the pick. "I also admire the fact that he fights for the people and he also is going to fight for you. He is a solid, solid person."
NBC News reported in the wake of numerous media reports Thursday morning that Trump was set to pick Pence, that Trump made a flurry of calls late in the evening second-guessing the idea.
NBC quoted one anonymous source familiar with the candidate's thinking, saying Trump felt "painted into a corner" with Pence because of flaws and conflicts with the other finalists, former House Speaker New Gingrich and New Jersey Gov. Chris Christie.
Trump viewed Gingrich as "too volatile" on the campaign trail. Christie was said to be a better fit for Trump, but his previous prosecution of Charles Kushner, father of Trump's son-in-law Jared Kushner, who has become a close Trump confidant, tore at Trump's family loyalties.
Paul Manafort, Trump's chief campaign strategist, denied reports there was any wavering in the Pence selection. He said the calls Thursday night were more about delaying the rollout as the scope of the Nice, France, terrorist attack was becoming clear.
At Saturday's press conference, Trump noted the difference between Pence and "crooked Hillary Clinton," saying that Pence would not be afraid to use the phrase "radical Islamic terrorism" and the he would serve as a partner to "fix our rigged system."
He also commented on the "Never Trump" movement, which sought to derail Trump's nomination saying, "They got crushed." The group was resoundingly defeated, with only a dozen holdouts protesting Trump's nomination on the convention's 112-member rules committee.
Trump added that Pence would help him unite the Republican party and that the two "would have an incredible convention" in Cleveland.
"I think if you look at one of the big reasons that I chose Mike -- and one of the reasons is party unity, I have to be honest," he said. "So many people have said party unity. Because I'm an outsider. I want to be an outsider. I think it's one of the reasons I won in landslides."
Pence later came to the podium where he officially accepted Trump's nomination while praising him as a candidate.
"I accept your invitation to run and serve as vice president of the United States of America," Pence said. "Donald Trump is a good man and he will make a great president of the United States of America."
During his speech, Pence discussed his views on foreign policy during President Barack Obama's administration.
"History teaches us that weakness arouses evil. Hillary Clinton and Barack Obama's foreign policy of leading from behind, moving red lines, feigning resets with a resurgent Russia and the rise of ISIS is a testament to this truth of history and we must bring a change to America's stand in the world," he said.
Following the press conference Pence tweeted a link to a fund raising effort for the campaign along with a message in support of Trump.
"Join me and [Donald Trump] to come together -- as a party, and a people, and a movement -- to Make America Great Again!" Pence wrote.