The 2004 Republican National Convention took place from August 30 to September 2, 2004, at Madison Square Garden in New York City, New York. The convention is one of a series of historic quadrennial meetings at which the Republican candidates for president and vice president, and party platform are formally adopted. Attendance included 2,509 delegates and 2,344 alternate delegates from the states, territories and the District of Columbia. The convention marked the formal end of the active primary election season. As of 2023^[update], it is the most recent major-party nominating convention, as well as the only Republican National Convention, to be held in New York City.

The theme of the convention was "Fulfilling America's Promise by Building a Safer World and a More Hopeful America." Defining moments of the 2004 Republican National Convention include a featured keynote address by Zell Miller and the confirmation of the nomination of President George W. Bush and Vice President Dick Cheney for reelection. Bush and Cheney went on to defeat the Democratic Party's ticket of John Kerry and John Edwards in the 2004 presidential election.

Apart from nominating a candidate for president and vice president, the 2004 Republican National Convention was also charged with crafting an official party platform and political agenda for the next four years. At the helm of the Platform Committee was United States Senator and Senate Majority Leader Bill Frist of Tennessee, Congresswoman Melissa Hart of Pennsylvania and Colorado Governor Bill Owens. The committee worked with the Bush campaign to develop the draft platform.

The platform adopted by the 2004 Republican National Convention was the longest in the party's history compared to the mere 1,000-word platform adopted at the first convention in 1856. At 48,000 words, it was twice the length of the one adopted at the 2004 Democratic National Convention which was only 19,500 words.

The choice of Madison Square Garden on January 31, 2003, by all 165 members of the Republican National Committee as the venue for the 2004 Republican National Convention meant that New York City would host a major Republican nominating convention for the first time in its history. On July 19, control of Madison Square Garden was officially handed over to the Republican Party under the administration of Chief Executive Officer of the Convention, Bill Harris. Mayor Michael Bloomberg thanked the party for their choice, for which he had vigorously lobbied, noting it as a significant display of support for the city and an economic boom.

Until Chicago, Illinois was selected as the host of the 2024 Democratic National Convention, 2004 was the last time that for either major party that they chose to hold their convention in a state that was not considered to be a swing state (the Democrats held their 2004 convention in Boston, Massachusetts).

Like the 2004 Democratic National Convention in Boston, Massachusetts, the Department of Homeland Security (DHS) officially declared the 2004 Republican National Convention a National Special Security Event (NSSE). As such, the United States Secret Service was charged with employing and coordinating all federal and local agencies including the various bureaus of DHS, the FBI, and the NYPD to secure the venue from terrorist attacks. Expected security expenditures reached $70 million, $50 million of which was funded by the federal government.

The city employed an active beat of 10,000 police officers deployed as Hercules teams—uniformed in full riot gear and body armor, and equipped with submachine guns and rifles. Commuter and Amtrak trains entering and exiting Penn Station were scoured by bomb-sniffing dogs as uniformed police officers were attached to buses carrying delegates. All employees of buildings surrounding Madison Square Garden were subjected to thorough screening and background checks.