Marley took over at the Broadfield Stadium in May 2007, since when Town have twice been promoted and just finished 10th in their first season in League One.
He told the club website: "I first joined the board in 1999 when we were in the Dr Martens League. Working full-time for the Crawley Town cause for the last 14 years has been personally worthwhile and seeing our rise up the football pyramid has been immensely satisfying.
"In Dave I think we have a worthy successor. He is very passionate about this football club and wants to help take it forward and continue to build on the foundations we have put in place. I will still be attending every game. The club is in my blood and always will be."
Pottinger, who has been a club director for three years, added: "Vic is one hell of an act to follow but it is an honour and a privilege that he recommended me to the board for the job and I am delighted to accept.
"The club is in a great position now, on and off the field, to really grow and establish itself at this level and perhaps push into the Championship."