Peter Lynn, who saw homelessness rise 33% during his five years as head of the Los Angeles Homeless Service Authority, said he would leave the job by Dec. 31.
"Over these five years of explosive growth, LAHSA deployed more than $780 million in new funding to address homelessness. We doubled our staff and then doubled it again," Lynn said in a written statement.
"We built and rebuilt our internal infrastructure, and worked with our community-based providers to expand theirs," he said.
The agency said its chief program officer, Heidi Marston, would serve as acting director during a nationwide search for Lynn's replacement.
As in San Francisco to the north, Los Angeles city officials have come under increasing pressure to reduce the growing homeless population, which has swelled by 12% during the past year as a shortage of affordable housing deepens in Southern California.
Overall, an average of nearly 59,000 people were sleeping on sidewalks, in makeshift tents, in abandoned vehicles or in shelters and government-subsidized "transitional housing" on any given night in Los Angeles County, according to a June study by the agency.
In August an audit by the city's controller found that the Los Angeles Homeless Services Authority had missed its goals of placing transients in permanent housing by wide margins.
In September, U.S. Housing and Urban Development Secretary Ben Carson rejected requests from California for more money from the Trump administration to fight homelessness, blaming state and local leaders for the crisis.
The Washington Post reported in November that White House officials were readying a plan to crack down on homelessness in Los Angeles and other major California cities.
Mayor Eric Garcetti, who has been criticized for failing to solve the crisis in his city, praised Lynn."Peter’s leadership of LAHSA came at a time when Angelenos took historic action and made generational investments in confronting the homelessness crisis. He served for five years, with dedication, in one of the toughest jobs — and I thank him for all he did to bring more resources to our most vulnerable neighbors," Garcetti said in a written statement.