The Northwestern Hawaiian Islands or the Leeward Islands are the small islands and atolls in the Hawaiian island chain located northwest (in some cases, far to the northwest) of the islands of Kaua'i and Ni'ihau. All the Northwestern Hawaiian Islands are uninhabited. They are administered by the U.S. state of Hawai‘i except Midway Atoll, which has temporary residential facilities and is administered by the U.S. Fish and Wildlife Service.

The Northwestern or Leeward Hawaiian Islands include:

• Ka‘ula
• Nihoa
• Necker (Mokumanamana)
• French Frigate Shoals (Mokupāpapa)
• Gardner Pinnacles (Pūhāhonu)
• Maro Reef (Nalukakala)
• Laysan (Kauō)
• Lisianski (Papa‘āpoho)
• Pearl and Hermes Reef (Holoikauaua)
• Midway (Pihemanu) (temporary residential facilities)
• Kure (Kānemiloha‘i)

The Northwestern Hawaiian Islands were formed over the same volcanic hotspot that formed the Emperor Seamounts and the Windward Hawaiian Islands. As the Pacific Plate moved north and later northwest over the hot spot, volcanic eruptions built up islands. The isolated land masses gradually eroded and subsided, evolving from high islands to atolls (or seamounts north of the Darwin Point).

• Hawaiian Islands National Wildlife Refuge