As explained in NE Boat Street, NE Northlake Way was originally Lake Avenue in the 1890 Brooklyn Addition to Seattle, so named because it ran along the northern shore of Lake Union. I couldn’t find an ordinance changing its name from Lake Avenue (used elsewhere, notably for what are now Westlake Avenue and Fremont Avenue N and for part of Eastlake Avenue E) to Northlake Avenue, but the latter name begins to appear in local newspapers in 1901. (Complicating matters slightly, the street appears as North Lake Avenue in the state’s 1907 plat of Lake Union Shore Lands.) Northlake Avenue began being referred to as Northlake Way in 1935, and this was made official in 1956.
Today, NE Northlake Way begins at the west end of NE Pacific Street under the University Bridge at Eastlake Place NE, and continues 1½ miles west to just shy of the Aurora Bridge, where it becomes a private road through formerly industrial land developed by the Fremont Dock Company into a business park. (The Puget Sound Business Journal and The Seattle Times have good articles on how over the years Suzie Burke transformed her father’s Burke Millwork Co., which opened in 1939, into what is today home to local offices for Google and Adobe and corporate headquarters for Tableau and Brooks Sports, among other tenants.) This private roadway continues for ⅖ of a mile beyond the end of the public right-of-way to the intersection of N Canal Street, N 34th Street, and Phinney Avenue N.
NE Northlake Way once began ⅖ of a mile further east, at NE Columbia Road on the University of Washington South Campus, but this stretch was changed to NE Boat Street in 1962, not without some controversy.