Mr. Obama said he had instructed U.N. Ambassador Susan Rice to sign the document next week, joining 140 other nations.
"It's the first new human rights convention of the 21st century," Obama said at the White House during an East Room celebration of the 1990 Americans with Disabilities Act.
The law protects people with mental or physical disabilities from discrimination in employment, education, housing, public transportation and other areas of life.
"This extraordinary treaty calls on all nations to guarantee rights likes those afforded under the ADA," Mr. Obama said. "It urges equal protection and equal benefit before the law for all citizens. It reaffirms the inherent dignity and worth and independence of all persons with disabilities worldwide."
The Senate will have to ratify the treaty.
Mr. Obama said 650 million people, or 10 percent of the world's population, live with a disability. In the U.S., 54 million people are disabled, he said.
Ninety percent of children with disabilities in developing countries don't attend school, and women and girls with disabilities often face deep discrimination, Obama said.
"Disability rights aren't just civil rights to be enforced here at home. They are universal rights to be recognized and promoted around the world," the president told an audience whose members included some of the people who helped get the law through Congress, such as former Attorney General Dick Thornburgh.
Also present were New York Gov. David Paterson, who is legally blind, and Tammy Duckworth, an assistant Veterans Affairs secretary and former Illinois National Guard major who lost both legs and partial use of an arm during a rocket-propelled grenade attack in Iraq in 2004.
There was a personal side to Friday's celebration for Mr. Obama.
His late father-in-law, Fraser Robinson, was diagnosed with multiple sclerosis in his 30s. But he never complained, never sought special treatment and never missed a day of work although he eventually needed two canes to help get himself there, Obama said.
Mr. Obama said Robinson did all of that, and more, before the ADA was passed, one of many quiet heroes who showed that people with disabilities "can be full contributors to society regardless of the lack of awareness of others."
"I think about him all the time when I think about these issues," Mr. Obama said.