The hospital specializes in the care of infants, children, teens, and young adults aged 0–21 in several specialties.

It moved to a cottage on Queen Anne Hill the next year, and in 1911 influential community members including Herbert Gowen and Mark A. Matthews dedicated a full 40-bed hospital at the same location.

[11] In 2008, the hospital was awarded Magnet recognition by the American Nurses Credentialing Center (ANCC) and was recognized again in 2013.

The expansion included a new cancer and critical care unit as well as a new emergency department with 38 exam rooms.

[20] The same year, its Research Institute received a $3M donation from the BMGF for an Infant Breathing Support Invention.

[28][29][30] In 2015 the hospital warned the public that due to its improper sterilization of surgical equipment, around 12,000 children and young adults treated there since 2010 were at risk of infection from bacteria or blood-borne viruses, including hepatitis B and C and HIV; it had issued a similar warning two years earlier.

[31] From 2001 on, it was revealed that a strain of deadly mold in the air handling systems of operating rooms (Aspergillus) was detected by hospital administrators.

[34] In early 2020, the health inspectors from the State of Washington came in and questioned hospital authorities on why HEPA filters were not installed in the ORs.

[40] As of 2020 Seattle Children's has placed nationally in all 10 ranked pediatric specialties on U.S. News & World Report.