The station and surrounding area are named after HMS Tamar, once the headquarters of the Royal Navy in Hong Kong.

[4] The government gave the Mass Transit Railway Corporation first refusal on the 60,000-square-foot (5,600 m2) site, which was sold to it in 1976 for around HK$200 million for cash and equity consideration.

On 12 February 1980, the segment of the Kwun Tong line between Central and Tsim Sha Tsui was opened.

[13] The expansion brought new toilets in the paid area, a lift between the concourse and, ground level, and artwork in the station.

[14] 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.

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.

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.

[16] Temporary measures are undertaken during peak hours, including the deployment of additional station assistants, adjustment of escalator directions[17] and making pacifying announcements by local celebrities.

[19][20] The existing signalling system of Tsuen Wan line was planned to be upgraded by Thales Transport & Security in 2018 for long-term use.

These PIDS panels display a countdown to their next two trains, as well as simulations of real-time crowdedness on their respective platforms.

[10] The second, Urban Soundscape by Otto Li, is located along either side of the escalator shaft between the new and current stations.

[10] 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.

A major shopping centre, Pacific Place, is accessed through a pedestrian walkway from Exit F.[24] 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.