Hawthorn issued a media release on Tuesday afternoon in which it said Brown had advised the club he would not be extending his contract.
"While it is disappointing to lose such a quality player, all clubs know their lists are vulnerable over this period with the entry of two new clubs," Hawthorn chief executive Stuart Fox said.
"The club and our members have loved the way Campbell has gone about his footy while at Hawthorn and we feel we have invested heavily over the years in developing him into the respected footballer that he is today.
"We thank him for his contribution while at Hawthorn."
Gold Coast confirmed in a release soon after that the defender, who has been the centre of intense speculation throughout 2010, would make the switch.
He will front the media with new coach Guy McKenna on Wednesday.
Talk of a possible defection first surfaced after his name was mentioned during last year's trade period when the Hawks tried to find an appropriate deal to secure Shaun Burgoyne.
The 27-year-old was not traded but there was a feeling that as Brown's name had been mentioned, irreparable damage had been caused.
Brown was drafted with pick 32 in the 2001 national draft and played 159 games in nine seasons for the Hawks, including the club's 2008 premiership win.
With Brown joining the Suns as an uncontracted player, the Hawks will receive a compensation pick in this year's NAB AFL Draft.
He follows Nathan Bock (Adelaide), Nathan Krakouer (Port Adelaide) and Michael Rischitelli (Brisbane Lions).
