The money is to be distributed among 11 agencies and used to create 180 new housing units in three counties, The Seattle Post-Intelligencer reported.
The foundation began its Sound Families initiative in 2000. The latest grant almost completes the promised funding.
A preliminary report by University of Washington researchers has found that about two-thirds of families who have been in the program have moved into permanent housing after spending an average of 13 months in transition.
"These organizations help put families back on the path to self-sufficiency by providing affordable housing paired with critical on-site services, such as job training, counseling and life skills classes," said Katie Hong, who heads the program while serving as interim director for Pacific Northwest giving for the foundation.