Duff signs for Fulham
Duff joined Newcastle from Chelsea during the summer of 2006, and went on to play 86 times, scoring six goals, the last of which came in the opening match of the Coca-Cola Championship season at West Brom.
"I am happy that my move to Fulham has been completed and look forward to joining in with the rest of the squad's training programme immediately in preparation for two important home matches this week," said Duff, who made his breakthrough at Blackburn, on Fulham's website.
"Fulham had a fantastic season last year and I know that having spoken to the manager in recent days that the club's ambitions remain high and I am looking forward to the challenges ahead."
The Cottagers finished seventh last season, qualifying for Europe. Roy Hodgson's men opened the new Barclays Premier League campaign with a 1-0 win at Portsmouth.
"I am delighted to add a player of Damien Duff's calibre to our squad, and welcome the further midfield options he provides us with," said the Fulham manager.
"I have known Damien for over a decade since he broke into the first team at Blackburn when I was manager, so I am fully aware of his qualities and I am looking forward to working with him again."
Fulham are also hopeful of completing a deal for South Africa midfielder Kagiso Dikgacoi, once a work permit has been rubber stamped.