Harris has scored three tries for Bradford this season

The 23-year-old joined from Canterbury Bulldogs midway through the 2005 season and scored 25 tries in 72 appearances for the club.

"The salary cap dictates what you can and can?t afford to pay players and we need to stay within it," said coach Steve McNamara.

"We offered him a new deal but we've been outbid and that is what happens."

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Harris made history when he became the first player to win successive Grand Finals in Australia and England when he was part of the Bulls' 2005 Grand Final-winning side, 12 months after winning the 2004 NRL Grand Final with Canterbury.

"I have really enjoyed my time with the Bulls and in the past couple of years I have learned a lot from the coaching staff," said Harris.

"I feel the time is right to return to Australia and I am really looking forward to joining the Cowboys."

The Cowboys were clearly delighted to have got their man.

"Following Paul Bowman's decision to retire, centre was an area we were looking to strengthen," said chief executive officer Peter Parr.

"Ben's signing certainly achieves that goal."