The station is served by Sound Transit's Link light rail system and is located near the intersection of Broadway and East John Street.

[3] The western slope of Capitol Hill has the highest population density of any area in Washington state,[4] with 55,000 people per square mile (21,000 per km2).

[6] Urban planner Virgil Bogue's rejected 1911 comprehensive plan for Seattle envisioned a citywide subway system, including an underground loop on Capitol Hill and Broadway that would connect with an east–west line on Pike Street.

[13][14] Voters rejected the $6.7 billion proposal, including a 69-mile (111 km) light rail system connecting Seattle to Bellevue, Washington, Lynnwood, and Tacoma.

[15] In November 1996, voters approved a condensed $3.9 billion regional transit plan that included a tunneled light rail station under Capitol Hill.

[17] The project's draft environmental impact statement, released in December 1998, determined that the Capitol Hill tunnel would be feasible and recommended its inclusion in the plan.

[19][20] Seattle representatives proposed an additional Capitol Hill station, near Broadway and East Roy Street, but it was left out of the preferred alternative due to cost concerns.

[21] In November 1999, Sound Transit finalized its preferred alternative, adding a crossover north of Capitol Hill station near East Thomas Street.

[27] Sound Transit, faced with budget issues and further schedule delays, deferred construction of the segment between Downtown Seattle and the University District in 2001 while re-evaluating alignment options.

[28] In 2004, Sound Transit selected a new tunnel route that crossed the Lake Washington Ship Canal at the Montlake Cut, to the east of the Portage Bay area.

[37][38] Demolition of buildings on the station site began in March 2009,[39] shortly before the formal groundbreaking for the University Link project,[4] and was completed by August.

[39][43][44] Many of the displaced and nearby businesses moved to the northern end of the Broadway district during construction, relying on mitigation funds from Sound Transit and the neighborhood's chamber of commerce.

[54] Construction on the west entrance and its cut and cover tunnel under Broadway required the street to be closed and rearranged several times beginning in November 2013.

[64] Two sets of escalators and elevators lead upward from the platform to two mezzanines at the north and south ends of the station, connecting to three surface entrances.

[70] Capitol Hill station houses most of the University Link tunnel's support systems, including power, communications, and ventilation.

[76] Capitol Hill cartoonist Ellen Forney has two murals in the station's north and west entrances, Crossed Pinkies and Walking Fingers, which portray simple, large hands outlined against a bright red background.

[75] The murals, which consist of porcelain enamel on steel panels,[77] are meant to evoke a sense of "coming together [whilst] pulling apart", with both playfully leading passengers from street level into the station.

[89] The staging areas used during the construction of Capitol Hill station were reused for a large transit-oriented development managed by Sound Transit and the City of Seattle.

The development, spread across four seven-story buildings on 2 acres (0.81 ha) between Broadway and 10th Avenue East, includes 428 apartments (of which 42 percent are designated as affordable housing), retail space, a community center, plaza, bike facilities, and a permanent venue for the local farmers' market.

[101] Capitol Hill station is part of the 1 Line, which runs from between Lynnwood, the University of Washington campus, Downtown Seattle, the Rainier Valley, and Seattle–Tacoma International Airport.

[103] King County Metro operates several bus routes that converge at Broadway and East John Street, traveling west towards Downtown Seattle and South Lake Union; east towards Volunteer Park and the Central District; south towards First Hill, Beacon Hill, and the Rainier Valley; and north towards the University District.

[104][105] On weekends during the spring, summer, and early autumn, a Trailhead Direct shuttle connects Capitol Hill station to North Bend and Mount Si, a popular hiking area.