The Hollywood star has dropped his sister Lee Anne DeVette as his publicist after less than two years and hired a public relations expert who specialises in keeping his clients' personal lives out of the limelight.
Cruise praised his sister for doing "a wonderful job", but said that from now on, she would just handle his charitable work.
In her place he has appointed Paul Bloch of the PR firm Rogers & Cowan to look after his personal publicity and that of his production company.
Since Ms DeVette took over Cruise's PR from his previous publicist, Pat Kingsley, in March 2004, the actor has rarely been out of the headlines, speaking about his fervent belief in Scientology and publicly mooning over his new love, Katie Holmes.
In a statement, Cruise said his sister had "always expressed a desire to oversee and expand the day-to-day activities of my charitable endeavours".
"This seemed an appropriate time to make that segue and bring Rogers & Cowan on board to handle mine and the company's entertainment-related publicity needs."
Ms DeVette, a fellow Scientologist, said she was looking forward to publicising her brother's involvement in social reforms, children's health issues and the "general betterment of the human condition".
"I know how important Tom's charitable goals are to him," she said.
Cruise, who shot to fame for his boyish good looks in Top Gun and Cocktail, was once considered shy of the media. But recently he has clashed in public with the actress Brooke Shields over her use of psychiatric drugs following her pregnancy and become increasingly vocal about his belief in Scientology.
Earlier this year, he embarked on a relationship with the Dawson's Creek star Katie Holmes, which prompted him to leap up and down on the sofa in an appearance on Oprah Winfrey's US talk show declaring: "I'm in love! I'm in love!"
Dismissing media claims that their romance was a stunt to gain publicity for their respective film releases, Cruise proposed to Holmes at the top of the Eiffel Tower in June after a whirlwind romance.
Last month, the couple announced they were expecting their first baby.
Cruise also suffered public embarrassment when water was squirted in his face at the London premiere of War of the Worlds in June.
Mr Bloch told the Los Angeles Times: "I think Tom has handled it magnificently and I think Lee Anne has handled it magnificently and I'm so pleased they brought us on."
It is not clear to what extent Mr Bloch will deal with Scientology-related issues.
The public relations expert Mark Borkowski said the appointment of Mr Bloch, who also represents John Travolta, Bruce Willis and David and Victoria Beckham, demonstrated a shift in Cruise's approach to media relations. "Paul Bloch is a very astute operator and it strikes me that he will want some sort of privacy. He is old school.
"Rogers and Cowan are not proactive PRs. They are not people who stage stunts. They have gone for him for a certain amount of protection. Paul Bloch's clients do not need publicity. This is a very conservative route to take in terms of PR. Rogers & Cowan are not people who jump up and down."
Max Clifford, the PR expert, said: "The only good press for the major stars is perfect. Unless everything they read and see says exactly what they want it to, it's the fault of someone."
The Welsh singing sensation appointed her mother Maria as her manager after sacking her former manager Jonathan Shalit in 2000. Two years later she sacked her mother following disagreements about her then boyfriend, although she was careful to praise her for doing an "amazing job" and for being a "terrific mother".
As the child star of Home Alone, Culkin's father Kit was his manager. Culkin senior gained a reputation for aggressiveness, but when Macauley was 14, his parents split and he refused to see his father. Stories about the teenage star's partying subsequently began to appear in the press.
During a prolific career as a child actress, making five films before the age of 11, Shields's mother Teri was her manager. It was not until she turned 30 that she fired her, giving her acting career an instant boost with a role in the sitcom Suddenly Susan.