Mr McCain is to take the stage to formally accept his party's candidacy for November's presidential election.
He will pledge to reach out to anyone "to get this country moving again", according to advance speech excerpts.
His running mate, Sarah Palin, has been formally nominated as the party's first female vice-presidential candidate.
She becomes only the second woman, the first being Democrat Geraldine Ferraro in 1984, to run for the US vice-presidency.
She mixed praise for Mr McCain with stinging attacks against Democratic presidential candidate Barack Obama in a speech on Wednesday night that energised the convention.
Mr McCain, in his speech, will promise change and a bipartisan approach to governing that overcomes the "constant partisan rancour" that prevents politicians resolving problems.
"Let me offer an advance warning to the old, big spending, do nothing, me first, country second Washington crowd: change is coming," he will say.
"Again and again, I've worked with members of both parties to fix problems that need to be fixed. That's how I will govern as president."
He will continue: "I have that record and the scars to prove it. Senator Obama does not."
The much-anticipated speech, scheduled for 2030 (0230 GMT), will bring to a close the party's four-day event.
Vindicated
In a rousing address which delighted the convention, Mrs Palin attacked Mr Obama as having talked of change, but done nothing of substance.
She accused him of being more interested in high flown speech-making than acting for real Americans, while she would challenge the status quo and work for the common good.
The BBC's Jonathan Beale, in Minnesota, says John McCain now has to switch the focus from Sarah Palin to himself - although she may have helped to do that as Mr McCain and the party believe they have now been vindicated in their selection of the Alaskan governor.
Our correspondent says Mr McCain will have to underline his policy proposals and flesh out what he would do differently from a Bush administration.
John McCain acknowledged as much when discussing his speech in an interview on US television earlier on Wednesday.
"The important thing right now is to tell Americans why I can restore our economy, get them affordable and available health care, a decent education, get these jobs back... and keep our nation secure," he told ABC News.
He also said he would refrain from much direct criticism of Mr Obama, despite some harsh put-downs from his rival when addressing his own party convention in Denver last week.
With memories of Mr Obama's well-received address before 80,000 people at Invesco Field still fresh, Mr McCain will face inevitable comparisons.
Mr McCain has never been considered a great speaker, said one of his closest aides, Mark Salter, who added that his goal for Mr McCain was simply a smooth delivery.
President George W Bush has already strongly endorsed John McCain as the best man to succeed him in the White House.
He will pledge to reach out to anyone "to get this country moving again", according to advance speech excerpts.
His running mate, Sarah Palin, has been formally nominated as the party's first female vice-presidential candidate.
She becomes only the second woman, the first being Democrat Geraldine Ferraro in 1984, to run for the US vice-presidency.
She mixed praise for Mr McCain with stinging attacks against Democratic presidential candidate Barack Obama in a speech on Wednesday night that energised the convention.
Mr McCain, in his speech, will promise change and a bipartisan approach to governing that overcomes the "constant partisan rancour" that prevents politicians resolving problems.
"Let me offer an advance warning to the old, big spending, do nothing, me first, country second Washington crowd: change is coming," he will say.
"Again and again, I've worked with members of both parties to fix problems that need to be fixed. That's how I will govern as president."
He will continue: "I have that record and the scars to prove it. Senator Obama does not."
The much-anticipated speech, scheduled for 2030 (0230 GMT), will bring to a close the party's four-day event.
Vindicated
In a rousing address which delighted the convention, Mrs Palin attacked Mr Obama as having talked of change, but done nothing of substance.
She accused him of being more interested in high flown speech-making than acting for real Americans, while she would challenge the status quo and work for the common good.
The BBC's Jonathan Beale, in Minnesota, says John McCain now has to switch the focus from Sarah Palin to himself - although she may have helped to do that as Mr McCain and the party believe they have now been vindicated in their selection of the Alaskan governor.
Our correspondent says Mr McCain will have to underline his policy proposals and flesh out what he would do differently from a Bush administration.
John McCain acknowledged as much when discussing his speech in an interview on US television earlier on Wednesday.
"The important thing right now is to tell Americans why I can restore our economy, get them affordable and available health care, a decent education, get these jobs back... and keep our nation secure," he told ABC News.
He also said he would refrain from much direct criticism of Mr Obama, despite some harsh put-downs from his rival when addressing his own party convention in Denver last week.
With memories of Mr Obama's well-received address before 80,000 people at Invesco Field still fresh, Mr McCain will face inevitable comparisons.
Mr McCain has never been considered a great speaker, said one of his closest aides, Mark Salter, who added that his goal for Mr McCain was simply a smooth delivery.
President George W Bush has already strongly endorsed John McCain as the best man to succeed him in the White House.
