Brian P. Golden, the longest-serving director of the Boston Planning and Development Agency, will end his tenure at the end of the month, the agency announced Thursday.

Golden, 57, a former state representative, was first appointed to serve as the agency’s executive director/secretary by the late mayor Thomas Menino in 2009. Later, in 2014, then-mayor Marty Walsh appointed Golden to the job permanently.

Golden’s departure comes as Mayor Michelle Wu searches to fill several other cabinet positions. It also clears the way for Wu, who campaigned on a slogan of abolishing the BPDA, to begin implementing her plan to reform the agency.

One first step the administration is said to be close to achieving on that front: hiring a Director of Planning, a new cabinet-level role that will play a central part in the forthcoming reform and oversee ongoing planning, zoning and development in the city. The new position will also effectively link the mayor’s office to the city's independent planning and development agency.

As director, Golden has overseen a rebranding of the controversial agency — known to long-time locals as the BRA, or Boston Redevelopment Authority — paved the way for its first-ever language access plan and shepherded it through an intense period of construction in Boston.

According to the BPDA press release announcing his departure, Golden has “managed over 20 million square feet of BPDA-owned property,” and “has steered more than 90 million square feet of development approvals through the BPDA’s permitting process.”

Since Golden’s permanent appointment, construction has begun on nearly 60 million square feet of projects.

Asked about a timeline, Wu said Thursday her administration would work as quickly as possible to fill the hole left by Golden’s departure.

“I’m very grateful to Director Golden for his years of service to the city and the BPDA,” Wu said, also pointing to the other ongoing searches for cabinet-level positions: a Boston Public Schools superintendent, a Boston Police Commissioner and a senior adviser to shape Boston's forthcoming Green New Deal.

“We’re looking on all of these to go as quickly as we can,” Wu said.