"On July 4, we are giving America a special gift," Salazar said at a news conference on nearby Ellis Island.
The statue was closed to the public after 9/11 because of security concerns. The base, pedestal and lower observation deck have since been reopened.
Salazar said he based his decision on an analysis of the structure completed last month by the National Park Service, including recommendations on reducing risk for visitors.
Thirty visitors an hour, chosen by lottery, will be allowed to visit the crown, which is accessible only by a narrow 168-step double-helix spiral staircase. Visitors will be brought to the crown in groups of 10, guided by a park ranger.
"We cannot eliminate all the risk of climbing to the crown, but we are taking steps to make it safer," Salazar said.
Safety measures include raising the handrails on the spiral staircase and stationing rangers throughout the statue to aid visitors.
Salazar also announced that $25 million in stimulus funding will be used for improvements at Ellis Island, the historic immigration center in New York Harbor. The work will include stabilizing a 1908 building and making repairs to the island's crumbling seawall.
The Interior Department said 40 percent of American citizens can trace a family connection to Ellis Island.
The Statue of Liberty will be open for the next two years. Then it will be closed again for more safety work.