Parker was the creative director and president of the iconic label's contemporary line. The brand also parted ways with runway collection designer Marios Schwab and investor Harvey Weinstein.
Parker's departure was reported earlier this week by Women's Wear Daily and Vogue. On Friday, WWD reported Schwab and Weinstein were out.
Bringing in Parker, Schwab and Weinsten was part of an effort to resurrect the Halson brand, which has had many ups and downs since its 1970s glory days, when it was helmed by the late Roy Halston Frowick and was synonymous with a sexy, slinky disco style.
Halston will not show a spring 2012 designer collection at New York Fashion Week, and instead will focus on the lower-priced Halston Heritage line, WWD reported.
The Associated Press contributed to this report.