PORTLAND — Daniel E. O’Leary, who led the Portland Museum of Art through 14 years of prosperity and growth, is returning to Portland to work with Maine philanthropist Roxanne Quimby as she unites her three charitable organizations around the central mission of improving the lives of Mainers.

Quimby introduced O’Leary at a private party at her West End home Tuesday night.

“The Portland Museum of Art under his leadership not only prospered financially, but was an anchor for the Arts District when the Arts District was really just a dream,” Quimby said. “By providing good leadership and strong anchorage on the top of Congress Street, the museum made it possible for Portland to became the city that it is today.”

She expects O’Leary, 67, to achieve similar successes with the Quimby charitable work and hopes that her initiatives create “a similar kind of anchor for a certain kind of creativity and vitality that we can do in our own way.”

O’Leary directed the museum for 14 years, beginning in 1993. Under his tenure, attendance increased from 88,000 annually to 150,000, and the budget grew from $1.8 million to $4.6 million. The endowment also ballooned, and O’Leary balanced the budget each year.

He also supervised two major building projects. He led the effort to restore the McLellan House and Sweat Galleries at the museum’s downtown campus, and purchased and began the restoration of the Winslow Homer Studio at Prouts Neck.

The Homer studio effort particularly caught Quimby’s attention, because of sensitive nature of discussions with the studio’s neighbors and the delicate aspect of the project itself. “It was a complicated situation, but he pulled it off,” she said.

O’Leary left the museum in 2008, and last year accepted a position as director of the Munson-Williams-Proctor Arts Institute in Utica, N.Y.

The offer to return to Portland was “unrefuseable” because of Quimby’s lofty goals. “She is the first person I have ever known who is fully aware of the deep solidarity among the different facets of life in Maine. She understands the linkage among the factory farms, the importance of preserving wilderness, the value of the arts, the role of the creative economy and how all of those things working together lead to job creation. Roxanne sees all of those things in the same arena.”

He will fill a CEO-type for Quimby operation, overseeing and managing Elliotsville Plantantion Inc., a private land conservation foundation; the Quimby Family Foundation, which awards grants to advance wilderness values and increase access to the arts; and the Quimby Colony, an urban artist-in-residence program in Portland.

O’Leary will start his new duties immediately.