Moran's appointment is the first sign that the agency is strengthening its management team following its buyout from Havas last month. The France-based holding company had held a significant minority stake.
Steve Aldridge, the agency's creative partner, will retain overall creative control of the agency.
Moran was Partners Andrews Aldridge's first high-level creative hiring when he joined in December 1998, four months after the agency was founded by Aldridge and Phil Andrews.
Moran joined from the then Wunderman Cato Johnson, where he had worked with Aldridge, who was previously its creative director.
Before joining WCJ, where he was the head of copy, Moran spent four years at GGT Direct and also worked at CDP and Saatchi & Saatchi.
Aldridge said: "Shaun has been my right-hand man for five years and has been running the creative department day to day. It felt natural he should have the title that went with his responsibility."
Moran said: "I've always wanted to be creative director of a top creative agency and I'm determined that Partners Andrews Aldridge remains that way."