Trump's 11th-hour detour from the campaign trail to plug his business acumen drew criticism from some of his fellow Republicans, but the former reality TV star said the project showed what he could accomplish.
Formally opening the Trump International Hotel in Washington, which has been in business since last month, Trump said he would bring the same principles to running the federal government that he has used as a real estate developer.
"My theme today is five words: under budget and ahead of schedule. That's what we do," Trump said at a ceremony in a hotel ballroom.
"This is what I want to do for our country," he said. "A project like this demonstrates what is possible when a team works together for a totally common purpose. It also shows how to work with government and to get things done."
Trump, making his first run for elected office, often highlights his business accomplishments and has held numerous events at his properties since launching his White House bid last year, including a trip to Scotland to open a refurbished golf resort in June.
But his Democratic opponent in the November 8 election, Hillary Clinton, and other critics have pointed to Trump's many failures and bankruptcies in his long business career.
Trump trails Clinton in opinion polls. From Washington, he was headed for campaign events in North Carolina, one of the key states that could determine who wins the White House. On Thursday, he heads to Ohio, another battleground state.
At the ceremony, Trump said that after a successful business career he wanted to "give back" and embark on a national plan of revitalization for poor communities and ailing infrastructure.
"The American people know what this election is about and they see it every time they get their healthcare bills in the mailbox or ride down a highway that's broken or go to an airport that looks like it's from a Third World country," he said.
The break from the campaign trail for a business event so close to the election was unusual for a presidential candidate. Trump campaign manager Kellyanne Conway said in several television interviews that the Washington event would not take away focus from the campaign and was "a quick pit stop."
Asked after the event why he was in Washington instead of campaigning in a battleground state, Trump told CNN it was "a very rude question" and said he worked hard on the trail every day.
"I can't take one hour off to cut a ribbon at a one of the great hotels of the world? I mean, I think I'm entitled to it," Trump told ABC News. He said there was a double standard, noting that Clinton was not criticized for taking time to see the singer Adele in concert on Tuesday night.
"It's so unfair because, you know, Hillary Clinton goes to see an Adele concert last night, and everybody says, 'Oh, wasn't that nice.
But Republican strategist Steve Schmidt, who led 2008 Republican presidential nominee John McCain's campaign, said the hotel stop was the latest inexplicable act from Trump and was atypical behaviour for someone trying to win the White House.
"The walls are collapsing," Schmidt told MSNBC in an interview. "He is not doing any of the normal activities that you'd be doing 13 days out in a presidential race for somebody who's competitive. You don't take a time-out to tend to your business interests."
Newt Gingrich, a former speaker of the US House of Representatives and one of the few prominent Republicans who has continued to actively back Trump's tumultuous campaign, said Trump's appearance hit the right message.
"I think it's a good campaign event because it emphasizes under budget and ahead of schedule, and why a Trump government would be different from the bureaucratic, wasteful, slow system we have today," Gingrich told reporters.
Trump's 263-room luxury hotel in Washington's Old Post Office building, about a mile from the White House on Pennsylvania Avenue, has not escaped controversy during preparations for its launch.
Trump has sued celebrity chefs Jose Andres and Geoffrey Zakarian for backing out of plans to run a restaurant there amid Trump's harsh rhetoric towards Hispanics. Critics have also organised protests in front of the hotel. Earlier this month, its facade was sprayed with graffiti, NBC News reported.
On Tuesday, Trump stopped at his Doral National Golf Club in Florida as part of a campaign swing through the state, denouncing President Barack Obama's signature healthcare overhaul because of rising insurance premiums.
Clinton campaigned on Wednesday in Florida, where many public opinion polls show a tight race. An average of polls compiled by RealClearPolitics showed the two candidates close in Florida, with Clinton at 46.4 percent compared with 44.8 per cent for Trump in a race including third-party candidates.
Speaking at a rally in Lake Worth, Florida, Clinton slammed what she described as Trump's business practices.
"Today he's in Washington, DC, to open a new luxury hotel," she said to boos from the crowd. "While the hotel may be new, it's the same old story because once again ... he relied on undocumented workers to make his project cheaper. And most of the products in the rooms were made overseas. And he even sued to get his taxes lowered."
With the campaigns focussed on battleground states, Clinton has a strong lead in the race to secure the 270 Electoral College votes - or tally of wins from the states - needed to win the White House, according to results from Reuters/Ipsos States of the Nation project released on Saturday.