The station's livery is blue and white. Served by the largest number of lines of any MTR station at four: the East Rail line, the Tsuen Wan line, the Island line, and the South Island line, Admiralty is a major interchange station within the MTR network.

The station and surrounding area are named after HMS Tamar, once the headquarters of the Royal Navy in Hong Kong. It was built on the former site of the naval dockyards, which were built in 1878 and demolished in the 1970s. The Chinese name, which translates to "gold clock", refers to a clock with gold-coloured numerals and hands that was located on the main building of Wellington Barracks from 1890 to 1962.

Between 2011 and 2016, the station underwent major expansion to accommodate two new sets of platforms underneath the original structure to serve two more MTR lines, the South Island line and the East Rail line (part of the Sha Tin to Central Link project). The South Island line opened in 2016, while the East Rail line platforms opened on 15 May 2022. Accommodating over 100,000 passengers per peak hour, it has since become the busiest station in the MTR network.

The government gave the Mass Transit Railway Corporation first refusal on the 60,000-square-foot (5,600 m) site, which was sold to it in 1976 for around HK$200 million for cash and equity consideration.

The Admiralty Centre, United Centre and Queensway Plaza commercial buildings formed part of the development, and sit directly above the station.

On 12 February 1980, the segment of the Kwun Tong line between Central and Tsim Sha Tsui was opened. At the time, Admiralty and Central stations were the only two MTR stations on Hong Kong Island. The platforms began serving the Tsuen Wan line on 17 May 1982.

Admiralty was designed to be a transfer station with the then-planned Island line. On 31 May 1985, the first phase of the Island line (between Admiralty and Chai Wan) opened, with Admiralty the temporary western terminus of the Island line. To facilitate cross-platform interchange, the Tsuen Wan- and Chai Wan-bound platforms were located on a very wide island platform on the lower level, while the Central-bound and termination platforms shared another very wide island platform on the upper level. When the second part of the Island line (Admiralty to Sheung Wan) opened in 1986, the termination platform became the Sheung Wan-bound platform, while the other platforms remained unchanged. In 2014, the Sheung Wan-bound platform became the Kennedy Town-bound platform.

At 9:14 a.m. on 5 January 2004, 14 passengers suffered minor injuries when a 55-year-old man suffering from delusional disorder ignited two gas cylinders full of paint thinner in the first train car of a Central-bound train from Tsim Sha Tsui. The driver decided to complete the journey and passengers were evacuated from the train in Admiralty.

Admiralty station was expanded to serve two additional lines - the South Island line on level L6 and the East Rail line on level L5.

The South Island line platforms opened on 28 December 2016, after a public open day on 24th of that month, giving residents in the Southern District quicker access to Hong Kong Island's central business district. The opening date was delayed from 2015 due to technical problems in the deep tunnels for the new platforms. During the Central Station crash, Admiralty was the southern terminus of the Tsuen Wan line. The East Rail line began servicing Admiralty on 15 May 2022, allowing commuters from the northeast New Territories to travel directly to Admiralty.

A new single level underground transfer lobby with natural light was built to the east of the original concourse, allowing passengers to transfer to the new lines. The atrium was also expanded. The station extension, located under Harcourt Garden, incorporates 34 escalators and five lifts to integrate with the existing station. The East Rail line takes up one level under the transfer lobby, with the South Island line being directly below it. Exits E1 and E2 were rebuilt as one exit to accommodate the glass roof of the interchange concourse and has since opened. While the East Rail line tracks will have sidings for terminating trains south of the station, the South Island line tracks end at bumper blocks north of the station with no overrun track.

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  South Island line Platform 5
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  South Island line Platform 6
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  New toilets on Level 5 in paid area
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  An image of when SCL platforms were still behind hoardings
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  Signs directing passengers to the newly opened South Island line on its opening day (28 December 2016)

The narrowest part of the existing platforms on L3 was widened to provide better access to the first and second cars of the Tsuen Wan line trains, as well as last two cars of Island line trains. Island line passengers travelling towards Tsuen Wan now have easier access to these cars. The expansion brought new toilets in the paid area, a lift between the concourse and, ground level, and artwork in the station.

The expansion works saw the station size being expanded significantly. The number of platforms doubled from 4 to 8, the number of floors increased from 3 to 8, and the number of escalators increased from 8 to 42.

Today, Admiralty station has a total of six underground floors; the uppermost (L1) floor has the fare control, lobby, shops, Customer Service Centre and other major facilities.

On floor L2, passengers can access Platforms 4 (Tsuen Wan line to Central) and 3 (Island line to Chai Wan). One floor down, on level L3, are Platforms 2 (Island line to Kennedy Town) and 1 (Tsuen Wan line to Tsuen Wan).There are very wide passageways between the two platforms on each of floors L2 and L3; they are also curved platforms with trains going in opposite directions. The platforms are in the shape of a trapezium. Because all the platforms are curved, there are large stickers in front of the platform screen doors with "Mind the gap" text, which can only be found in this station. (This can be seen in the image of Admiralty Station in this page.) Passengers travelling from Eastern District and Wan Chai District can walk across to platform 1 to board the Tsuen Wan line trains bound for Kowloon, Kwai Chung and Tsuen Wan. Passengers travelling from Kowloon, Kwai Chung and Tsuen Wan can walk across and board the Island line trains bound for Chai Wan from platform 3.

In the extension part built to the east of the original Tsuen Wan / Island line station box, a 30 metres (98 ft) tall atrium extends 5 floors below ground. Inside the atrium, there are five escalators from floor L2 (platforms 3 and 4), and another five from L3 (platforms 1 and 2), connecting to the circulation mezzanine on floor L5 under a semi-circular skylight that brings natural light in from Rodney Street. Through floor L5—the top level of a 24 metres (79 ft) span cavern—passengers could access the East Rail line platforms sited in adjoining tunnels on the same level, or reach the South Island line platforms below, which are located 34 metres (112 ft) below ground.

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  Toilets in the paid area next Exit E (May 2022)
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  L1 Concourse, near Exit E (May 2022)
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  L4 level transferway escalators (May 2022)
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  Level L5, transfer passageway between the two East Rail line platforms (May 2022)
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  L5, signs directing passengers to the Tsuen Wan and Island line platforms (May 2022)
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  East Rail line Platform 7 (May 2022)
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  Artwork on the Exit E concourse
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  Passengers waiting for Tsuen Wan-bound Tsuen Wan line trains on Thursday, 16 January 2020.

As the primary interchange point between the Tsuen Wan line, the Island line, the East Rail line, and the South Island line, Admiralty is heavily congested during rush hours.

Admiralty and North Point are the only cross-platform interchange stations on Hong Kong Island between lines serving it and Kowloon in the MTR system. It is also the only interchange station for the South Island line. Despite trains departing at capacity (every 2.1 minutes), commuters frequently have to board the second or even the third train when changing lines. The situation deteriorated following fare cuts following the MTR–KCR merger.

Temporary measures are undertaken during peak hours, including the deployment of additional station assistants, adjustment of escalator directions and making pacifying announcements by local celebrities. During evening peak hours, some Tsuen Wan line trains are taken out of service at Central, and placed back into service at Admiralty, in order to relieve the demand at Admiralty. The existing signalling system of Tsuen Wan line was planned to be upgraded by Thales Transport & Security in 2018 for long-term use.

In addition, the 2022 extension of the East Rail line (from Hung Hom to Admiralty) has helped to divert some cross-harbour demand from the Tsuen Wan line, thereby reducing congestion. New "Cross-Harbour Easy" panels have been installed on the concourse and Island line platform levels to help harbour-crossing passengers make an informed choice between the two lines. These PIDS panels display a countdown to their next two trains, as well as simulations of real-time crowdedness on their respective platforms.

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  Crowd waiting to transfer train at Admiralty
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  The busiest part of Admiralty during the evening peak hour – Tsuen Wan line platform for Tsuen Wan-bound train
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  The new concourse for the East Rail line and the South Island line becomes very crowded during the evening peak hours
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  A lot of passengers alighting from an East Rail line train

The station expansion project has brought three artworks to the station. The first is Sense of Green by Tony Ip, which is a new bamboo-covered landscaped deck over Harcourt Garden. The second, Urban Soundscape by Otto Li, is located along either side of the escalator shaft between the new and current stations. It depicts passengers' journeys through Admiralty. Anchoring the atrium is the suspended aluminium sculpture Mapping Our Journey by American artist Talley Fisher, representing the four MTR lines converging at the station as well as the intersection of individuality and community.

Admiralty is part of the central business district of Hong Kong Island. There are many office buildings around the station. A major shopping centre, Pacific Place, is accessed through a pedestrian walkway from Exit F.

• A: Admiralty Centre
• B: Drake Street, Lippo Centre
• C1: Queensway Plaza
• C2: Taxi stand
• D: United Centre
• E: Rodney Street, CITIC Tower
• F: Pacific Place

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  Exit E (Oct 2023)
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  Exit E (May 2022)
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  Exit E1 before its renovation (March 2010)

There is a bus terminus stretching across the length of Admiralty that can be reached from exits B, C2 and D. The terminus is served by buses that connect to many different parts of Hong Kong Island, Kowloon and the New Territories.

• Bus
  • KMB, serving only cross-harbour routes on Hong Kong Island
  • Citybus
  • Bus terminuses within walking distance of the station:
    • Admiralty (West) – Exit B
    • Admiralty (Tamar Street) – Exit B
    • Admiralty (Drake Street) – Exit C2
    • Admiralty (East) – Exit D
    • Admiralty (Rodney Street) – between Exit D

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