Three years after receiving nearly $5 million in federal funds to combat homelessness among young adults, Boston has housed more than 500 youths and added 277 housing units, an increase from just 40 units when the initiative launched in 2019, city officials said.

The effort has led to a 44 percent drop in individual youth homelessness, those ages 18 to 24, compared to the number of young people experiencing homelessness on a single night from 2019 to 2022, Boston Mayor Michelle Wu’s office said in a statement.

Wu said a lack of affordable housing is the city’s “most pressing challenge’’ with significant impacts on young adults.

“I’m grateful to the Office of Housing and all of our partners for working collaboratively to ensure that young adults have a safe and stable place to live,’’ Wu said in the statement issued Thursday.

The plan was launched under former mayor Martin J. Walsh, now serving as labor secretary in the Biden administration, in November 2019. At the time, the city estimated that about 325 people under the age of 24 were living on Boston’s streets or in its shelters. That number fell to 232 last January, and this month there were 106 single individual young adults sleeping in city shelters or outside, according to Alexander Sturke, a spokesperson for the mayor’s Office of Housing.

Ari Barbanell, executive director of Winter Walk, a Boston nonprofit that aims to end homelessness in the city, said Boston has made “tremendous gains’’ and an “incredible leap in progress’’ working to help homeless young adults in recent years.

“There is still much work to do,’’ Barbanell said in an e-mail Friday. “Unfortunately, too many youth go unseen and unserved.’’

The plan, dubbed “Rising to the Challenge,’’ sought to cut down youth homelessness by expanding access to housing and opportunities for education, employment, mentorship, and support from adults, the statement said.

In 2019, the federal Office of Housing and Urban Development awarded Boston $4.7 million to devote to building 157 new housing units for homeless young adults. At the time, the city had just 40 youth-dedicated housing units, the statement said.

Since the plan launched, the city has added 277 housing units for a total of 317 units dedicated for people age 24 and younger, the statement said.

City officials also launched a program to help 30 young people enrolled in Boston Public Schools who are homeless to navigate the city’s new housing opportunities, the statement said. The program expanded this year to include providing rental assistance for 15 BPS students.

The mayor’s office said it also collaborated with the Office of Workforce Development and Human Services to connect 40 young people placed in housing with opportunities to work and go to school, the statement said.

Officials said the plan, which was organized with the United Way of Massachusetts Bay and Merrimack Valley, has “completely redesigned the way the City responds to’’ youth homelessness and seeks to tailor resources and opportunities for each person’s needs.

Bob Giannino, president and CEO of United Way of Massachusetts Bay and Merrimack Valley, said homelessness among young people is one of the most difficult areas to address in the state’s housing crisis.

“Youth and young adult homelessness is a complex social problem with various underlying economic and social factors, such as a lack of affordable housing, physical and mental health issues, and a lack of behavioral health supports and career pathways,’’ Giannino said in the statement. “It is critical that we ensure disconnected and under-connected youth have access to strong postsecondary pathways and opportunities.’’

Nick Stoico can be reached at Follow him on Twitter @NickStoico.