Mr. Clinton made the announcement in a rare appearance in the White House's press briefing room at the start of McCurry's daily briefing.
"The long-awaited coup in the press office is finally taking place," President Clinton said. He said McCurry is departing "much to my regret."
Mr. Clinton said McCurry, who had served as State Department spokesman before moving over to the White House, had a good command of foreign policy and that he would be missed.
"Quite simply, Mike McCurry has set the standard by which future White House press secretaries will be judged," Mr. Clinton said. "In an age where Washington has come to be governed by a 24-hour news cycle and endless cable channels with their special niche audiences, Mike has redefined the job as press secretary in a new and more challenging era."
Lockhart was the spokesman for Mr. Clinton's 1996 re-election campaign.
"I am very fortunate to have in Joe Lockhart an outstanding successor for Mike," President Clinton said. "He is smart, he knows our policies foreign and domestic, and he has skillfully articulated them."