It’s the end of an era — Richard Johnson is leaving Page Six after nearly 25 years as editor of the world’s most famous gossip column.

Emily Smith, who cut her teeth on Fleet Street before coming to New York five years ago, will take over the reins next month when Johnson moves to Los Angeles.

“Emily is a star and we are thrilled with her reporting, writing and leadership,” said Post editor-in-chief Col Allan. “She is going to be a fixture in this town for a long time to come.”

Johnson, who led Page Six to its world-beating preeminence, is moving to Hollywood to work on new digital ventures for News Corp., the parent company of The Post.

“It’s bittersweet,” Allan said. “Richard is a great friend and we will miss him, but we’re excited for him, too.”

Johnson said he will miss Page Six — but not February in New York. “I love Page Six and The Post, but I’ve always wanted to give Los Angeles a try,” he said.

Allan said Page Six will continue its great tradition of spanning uptown and downtown, covering all the boldface names who make the Big Apple shine — from socialites to athletes to financiers, partygoers, party-throwers and everybody in between.

“This is the best gossip column in the world — and it’s only going to get better,” Allan said.