If there is a museum director who embodies Mayor Bill de Blasio’s commitment to empowerment and inclusion, it is Gonzalo Casals, who leads the Leslie-Lohman Museum of Art in SoHo, which is devoted to queer art. Now the mayor has given Mr. Casals a new title: New York City’s Cultural Affairs Commissioner, for the largest local funder of arts and culture in the United States.

“Art and culture should enrich the lives of all New Yorkers — not just a select few,” Mayor de Blasio said in a statement. “Gonzalo understands how to uplift the experiences of New Yorkers from all five boroughs.”

Mr. Casals is an immigrant from Argentina who identifies as queer. Since 2017, he has led the Leslie-Lohman, a museum with roots in the L.G.B.T.Q. civil rights movement, diversifying its collection and programming with contributions from the gay community. Mr. Casals previously served as deputy and interim director at El Museo del Barrio in East Harlem, a major center for Latino art and culture, where he stepped in after Margarita Aguilar left amid turmoil.

“I look forward to continuing to further the work that the agency has been doing,” Mr. Casals, who starts April 13, said in a telephone interview. “Opening up opportunities in the sector for folks like me — immigrant communities, queer communities, Latinx communities.”