His executive order gives a new task force 60 days to present plans, including a location, for the garden.
He insists the new statues must be lifelike, "not abstract or modernist".
A number of US statues have been pulled down since the police killing of an unarmed black man, George Floyd in May.
Monuments linked to the slave-owning Confederacy during the Civil War in America have been especially targeted in the nationwide protests ignited by the death of Floyd in Minneapolis, Minnesota, after a white police officer knelt on his neck for nearly nine minutes.
Trump has defended Confederate symbols as a part of American heritage.
In a speech to mark Independence Day at Mount Rushmore, he condemned the anti-racism protesters who toppled statues.
He said America's national heritage was being threatened - an emotive appeal for patriotism.
The garden - to be in a place of natural beauty near a city - is to be opened by 4 July 2026, Trump's executive order says. State authorities and civic organisations are invited to donate statues for it.
Trump's choice of historical figures to be commemorated in the garden is likely to be controversial.
The list of "historically significant" Americans includes predictably Founding Fathers like George Washington and Thomas Jefferson, but also frontiersman Davy Crockett, evangelical Christian preacher Billy Graham, Ronald Reagan and World War II heroes Douglas MacArthur and George Patton.
There will also be statues of African American civil rights campaigners Harriet Tubman and Martin Luther King Jr.
Controversially, Trump includes non-Americans who "made substantive historical contributions to the discovery, development, or independence of the future United States".
So the garden can have statues of Christopher Columbus, Junipero Serra and the Marquis de Lafayette.
Columbus and the Spanish Catholic missionary Serra are far from heroic for Native Americans, because their "discoveries" led to the enslavement and exploitation of indigenous people by white colonists.
America's early economic development also relied on slavery - which makes some of the traditional national heroes dubious for African Americans.
The Marquis de Lafayette, a French aristocrat and military commander, led American troops in key battles against the British in the American Revolution.