The former "Beverly Hills, 90210" actor also stars in, directs and is a producer on the dark comedy "Call Me Fitz."
He is to appear in the installments of "Haven" scheduled to air Aug. 5, Aug. 12, Aug. 19 and Sept. 9.
He is to direct the Sept. 9 program, as well.
"'In Haven,' Priestley plays Chris Weekly, a handsome but anti-social marine biologist who is forced to deal with an affliction most would consider a blessing -- everyone suddenly loves him and will do anything he wants. Only Audrey Parker [played by Emily Rose] seems unaffected by Weekly's 'charms,'" Syfy said in a synopsis.