The pair will clash at London's ExCel Centre on Saturday, December 9, two months before Harrison appears in court in Glasgow to answer charges of assault, breach of the peace and fraud.
Amir Khan's first eight-round contest will serve as chief support alongside British heavyweight champion Matt Skelton, both against opponents yet to be named.
Harrison, who pulled out of his last fight in Belfast in May at two days notice because of depression and alcoholism issues which saw him check into the Priory Clinic, claims he has been off the drink "for months and months."
He added: "I've been training for three or four months now and I've never felt fitter."
But he intends to stay out of Scotland by preparing at a secret training camp in southern Spain to escape media attention before arriving in London the week before the fight.
"It's easier being away from Glasgow. There's no temptation," he said.
Promoter allegedly said: "We would normally go to Scotland with Scott but because of his publicised problems we are bringing the fight to London.
"The broadcasters I am working with were worried that if the fight took place in Scotland and Scott pulled out they would be left without a main event."
Warren added: "He has been working hard on the other issues in his life and I commend him for that."
The 28-year-old champion was clearly up for the fight after flying into London from Spain today to announce it.
He insisted his problems were in the past, stating: "I feel as if I've come back stronger for it. I feel as though I've never been anywhere.
"He's a good challenger, he's undefeated but I don't see him going 12 rounds. I've watched his last few fights and he looks a bit rocky around the chin."
The 27-year-old Cook, from Dagenham, who gave up the British, Commonwealth and European titles to pursue his world championship ambitions, responded: "You've got it coming to you. Are you nervous already?"
Cook added: "He's just made for me in every way."
Harrison pointed out that the Cook camp had rejected a fight with him two years ago, claiming their man was not ready.
Cook countered: "I wanted to win the European title first."
Shrugging off any suggestion he would be distracted by his pending court appearance, Harrison said: "I can still stay focused, stay world champion and then go to court in February. I can use it as a positive, I'm a fighter."
Harrison, who will have been out of the ring of 13 months by the time he fights, was originally supposed to defend against interim challenger Juan Manuel Marquez in Glasgow on November 4, but the Mexican pulled out to take another fight in El Paso, Texas, next month.
Promoter Warren said: "We agreed with his management that such a big fight needed a bigger build-up but the winner will fight Marquez next year."
The ExCel bill will also feature Matt Skelton defending his Commonwealth heavyweight title against an opponent to be named next week.
Dagenham's Kevin Mitchell will also appear if he comes through successfully when he meets Ghana's George Ashia for the vacant Commonwealth super-featherweight title at York Hall, Bethnal Green, on October 28.
British light-heavyweight champion Peter Oboh will defend against Portsmouth's Tony Oakey in his first fight for two years, with Olympic silver medallist Khan figuring in an eight-round contest.
Must say i doubt Amir's fight will go eight rounds
