The creator of Harry Potter told Britain's media ethics inquiry that having journalists camped on her doorstep was "like being under siege and like being a hostage."
Miller said she felt paranoid, violated and anxious after years of car chases and intimate revelations.
"The attitude seems to be absolutely cavalier," Rowling said. "You're famous, you're asking for it."
Rowling told the inquiry she had gone to court or to Britain's press watchdog more than 50 times over pictures of her children or false stories, which included a claim by the Daily Express that unpleasant fictional wizard Gilderoy Lockhart had been based on her first husband.
Miller, 29, who hit the tabloids when she dated Jude Law, said the constant scrutiny left her feeling "very violated and very paranoid and anxious, constantly."
"For a number of years I was relentlessly pursued by 10 to 15 men, almost daily," she said. "Spat at, verbally abused."
"I would often find myself, at the age of 21, at midnight, running down a dark street on my own with 10 men chasing me. And the fact they had cameras in their hands made that legal," the actress added.
Rowling and Miller were among a cast of famous witnesses including actor Hugh Grant, a former aide to supermodel Elle Macpherson and the parents of missing and murdered children - who have described how becoming the focus of Britain's tabloid press wreaked havoc on their lives.
Rowling said she was not prepared for the media attention she began to receive when her first book, "Harry Potter and the Philosopher's Stone," became a sensation.
The seven Potter books have sold more than 450 million copies, spawned a hit movie series and propelled Rowling from a struggling single mother to one of Britain's richest people.
"When you become well-known ... no one gives you a guidebook," she said.
Prime Minister David Cameron set up the inquiry amid a still-unfolding scandal over illegal eavesdropping by the News of the World tabloid. Owner Rupert Murdoch closed down the newspaper in July after evidence emerged that it had illegally accessed the mobile phone voice mails of celebrities, politicians and even crime victims in its search of scoops.
More than a dozen News of the World journalists and editors have been arrested, and the scandal has also claimed the jobs of two top London police officers, Cameron's media adviser and several senior Murdoch executives.
The Associated Press contributed to this report.