The Magic FM DJ - known as Emma B – claimed he exposed himself to her when she walked past an alleyway in Greenwich, south London in 2008.
Ms Wilson, who waived her right to anonymity, told BBC Radio 4’s Woman’s Hour she recognised Couzens when she saw his picture in news reports.
She said she was “so very sure” it was him that it "adds to the clamour of chances there were to stop this man”.
Scotland Yard and police watchdog are now investigating.
Couzens, 48 - a Met officer when he kidnapped, raped and murdered 33-year-old Ms Everard in Clapham, south London in March - was given a whole-life term last month.
The Independent Office for Police Conduct is looking into the force’s handling of three other alleged indecent exposures involving Couzens, including one in south London said to have taken place three days before he murdered Ms Everard.
Ms Wilson told the BBC she knows it was Couzens who exposed himself to her as his “face stays with you”. At the time, he was a volunteer officer with Kent Police.
She explained how she ran into a nearby shop to alert police who then visited her to take a statement.
Ms Wilson claimed: “They were asking me what I could see... he was playing with himself and there were specifics about his state of arousal that they thought were quite amusing. It was really humiliating.
"I remember clearly saying to them, ‘I really hope this is all he needs to do’ and I said that at the time because I was so struck by how feeble their response was.”
The incident was “aggressive, it was purposeful, it was calculated”, the presenter added.
“It wasn’t this comic character that we have of this local peeping Tom or the local flasher in the flasher mac.
“There’s a really big part of me that hopes it wasn’t him because if it was this is horrific that it could have gone on for so very, very long.”
A Met spokesman said at the time a search of the area was conducted but the suspect could not be found.
CCTV inquiries were unsuccessful and the matter was passed to a local safer neighbourhoods team for intelligence.
The force said: “In terms of it being Wayne Couzens, to the best of our knowledge we are not aware of any reports prior to his March arrest when he was named as a suspect.
“If we receive any allegations we will access and investigate accordingly.
Following the launch of an independent inquiry and review into how Couzens became a police officer, the Met said it would re-evaluate its approach to indecent exposure.
Deputy Commissioner Bas Javid acknowledged on Tuesday there was a “crisis” of confidence in policing in the wake of Ms Everard’s murder.
Speaking to BBC Radio 4’s Today programme, he said: “We want women and girls particularly to feel safe in communities.
“There’s a lot of work to be done to rebuild that trust and give people the confidence to come forward.”