After heavy criticism over a series of failed sex crimes cases, the force will now put their role as investigators first, Met Commissioner Cressida Dick said.
Ms Dick said: "I arrived saying very clearly that we should have an open mind when a person walks in and we should treat them with dignity and respect and we should listen to them and we should record what they say.
"From that moment on, we are investigators," she added.
The remarks came as it emerged director of public prosecutions for England and Wales, Alison Saunders will quit when her five-year contract expires in October.
Ms Saunders came under fire after several rape trials collapsed amid allegations that evidence had not been disclosed.
Ms Dick said that in the past the police have been criticised for "not being open minded enough and sympathetic enough" to victims of sexual offences.
She said it was "very important" to encourage people to tell their story and she wants to go on "raising the confidence" of victims.
However, she added: "But actually our job is not all about victims. Our job in investigations is to be fair, to be impartial and when appropriate to bring things to justice.
"And, of course, to support victims. But it isn't ALL about victims."
Guidelines for police dealing with rape and sex assault cases were issued nationally after the Jimmy Savile scandal amid accusations that police had not properly investigated.
But officers came under fire after funnelling resources into a case about an alleged Westminster sex abuse ring, called Operation Midland, after allegations by a man known as Nick whose claims were deemed by officers to be "credible and true".
In 2016, Sir Richard Henriques, a retired judge, remarked on failings in Operation Midland and said that "the presumption of innocence appears to have been set aside".
Ms Dick, who took up the role as Commissioner in April 2017 after Operation Midland collapsed, said sexual offences are a "tremendously high-profile, tremendously contested and a tremendously politicised" area.
"I can understand why those who support victims will say, for example, victims must have anonymity in certain areas and it's very important that offenders don't have anonymity, because when an offender is named, other people may come forward. We do find that.
"I can equally understand that when you describe somebody as a sex offender or a rapist, their whole world may collapse.
"So it is really, really hard to know what protection should be in place for both. I'm glad there is a debate about it," she said.
In additional comments to the Times, Ms Dick reportedly added that she would not spend a lot of resources on cases that were "very trivial" or unlikely to result in conviction.
She reportedly added: "And what might be a misunderstanding between two people, clumsy behaviour between somebody who fancies somebody else, is not a matter for the police."