The first lady says the commander in chief has not had a cigarette in almost a year.
Michelle Obama says the president wants to be able to look their daughters in the eyes and tell them he does not smoke.
The president has said in the past that he used to light up about five times a day, a nicotine habit that began as a teenager.
"He's always wanted to stop," Michelle Obama said Tuesday.
The White House offered no details Tuesday, in keeping with its practice of trying to keep Obama's habit out of the spotlight.
Obama last addressed the question in June 2009.
The Associated Press contributed to this report.