Dan Evans told jurors yesterday his skills in getting hold of voicemail messages would bring in "big exclusive stories cheaply" during an interview with Mr Coulson, who later quit the paper to become Prime Minister David Cameron's communications chief.
He described it as a "ker-ching" moment that helped seal the £53,000-a-year post.
Evans told the jury he was involved in hacking at the Sunday Mirror for about 18 months from 2003 when he was given a job, but it had been going on before that.
He said he then met Mr Coulson, who is on trial with former colleagues on phone hacking charges, at a London hotel.
Evans told the trial: "I told him about my background, the sort of stories I had been doing. Almost the sort of stuff I had been through before.
"I got on to voicemails and interception and I told him I had a lot of commercially sensitive data in my head and how things worked at the Sunday Mirror and I could bring him big exclusive stories cheaply, which was the kerching moment. 'Bring exclusive stories cheaply' equals job."
One way to bring in exclusive stories cheaply was to listen to someone's voicemails and work out who they were having a relationship with, he said. He added that would "shift units from supermarket shelves".
On his first day at the News of the World in January 2005, Evans said he came armed with a suggestion for an investigative story, but was taken into a room and handed a list of names by a colleague, who cannot be named, the court heard.
They included Scots former TV presenter John Leslie, Heather McCartney, Esther Rantzen, Chris Evans, Ed Balls, Ronnie Biggs, Elle Macpherson, Michael Jackson and Sir Michael Parkinson among others.
Evans said he was rather "crestfallen" at being given the task. Asked what that task was, he said: "(The journalist) wanted me to hack the interesting names."
He told the court he would hack phones "probably most days" while at the News of the World, and that he had accessed voicemails more than 1000 times.
He claimed the newspaper used a company that could provide personal information including phone numbers, credit activity, telephone bills, medical and tax records within three hours.
Most of the NotW features department's budget went on paying for stories like kiss and tells, Evans told the jury.
He said: "Dark arts were applied to generate leads and tips which would often be locked down with the aid of a chequebook."
Evans has already admitted conspiracy to hack phones at the Sunday Mirror between February 2003 and January 2005, and the same offence at the News of the World between April 2004 and June 2010. He also pleaded guilty to conspiracy to commit misconduct in public office between January 2008 and June 2010, and perverting the course of justice by giving a false statement in High Court proceedings.
Mr Coulson, 46, of Kent, former News International chief executive Rebekah Brooks, 45, of Oxfordshire, and former NotW managing editor Stuart Kuttner, 73, of W Essex, deny conspiring to hack phones between 2000 and 2006.
Mr Coulson also denies two counts of conspiring with former NotW royal editor Clive Goodman, 56, of Surrey, and others to commit misconduct in a public office.
All seven defendants in the case deny the charges against them.
The trial continues today.