The Brunei–Malaysia border divides the territories of Brunei and Malaysia on the island of Borneo. It consists of a land border and substantial lengths of maritime borders stretching from the coastline of the two countries to the edge of the continental shelf in the South China Sea.
Brunei's 200 nautical mile continental shelf claim makes it a claimant of a portion of the South China Sea that is subject to multiple overlapping claims by China, Taiwan and Vietnam. Malaysia is also a claimant in the area but a bilateral agreement with Brunei has solved the overlapping claims over Brunei's territorial waters.
Land border The border
From west to east, the Brunei–Malaysia border begins where the watershed of the Baram and Belait river basins meet the South China Sea at a point six nautical miles (11 km) east of Tanjung Baram at coordinates .
It then travels along the watershed of the two river basins for about 30 km to the Pagalayan Canal. It then goes a further 44 km to the Teraja Hills. From there, the border runs along the watershed between the Belait and Tutong rivers on one hand, and the Baram and Limbang rivers on the other. It then proceeds along the watershed of the Brunei and Limbang river basins, enters and runs along Sungai Mendaun, Sungai Melais and Sungai Menunggul (Menunggol) until its estuary at Brunei Bay.
The land border between Malaysia and Brunei's Temburong District (which is separated from the other part of Brunei) starts at the estuary of the Pandaruan River and runs the entire length of the river to its source. It then runs along the watershed between the Temburong river on one hand, and the Limbang and then the Trusan rivers on the other until it reaches Brunei Bay. The northern terminus of this boundary is located at the mouth of the Sungai Bangau, based on the coordinates established by the Sarawak (Definition of Boundaries) Order in Council 1958.
Demarcation and Survey As of August 2026, 264.791 km or 50% of the total length of the land boundary has been demarcated and surveyed.
The demarcation and survey process commenced with the "Exchange of Letters" on 16 March 2009 which provided settlement on the status of both the maritime and the 528.45 km land border between the two countries. The Exchange of Letters affirmed five boundary agreements between Brunei and Sarawak from the British colonial ere, with a total length of 207.3 km, while the remaining parts of the border would determined by using the watershed principle to determine the remaining undelimited portions of the border.
Both countries signed the first Memorandum of Understanding for the completion of demarcation and survey of a portion of the border on 26 August 2024. Despite what has been described as slow progress, the demarcation and survey of the entire land boundary is targeted for completion by 2034.
For more details regarding the demarcation and survey, see The Exchange of Letters of 2009 section below.
Maritime borders
The border
Brunei's maritime boundary with Malaysia until the 100 fathom isobath was inherited from the (SI 1958/1517)and the (SI 1958/1518), both of which defined the boundary between Brunei on the one hand, and Sarawak and Sabah, Malaysia, on the other. All three territories were then ruled by Britain. The powers for the orders in council were derived from the British Colonial Boundaries Act 1895 (58 & 59 Vict. c. 34).
Brunei and Malaysia still adhere to the British Orders in Council to define their territorial waters, where it was referred to in the Joint Statement made after the 18th Annual Leaders' Consultation between the Sultan of Brunei and Prime Minister of Malaysia on 3 November 2014 when reference was made to the Sarawak (Definition of Boundaries) Order in Council 1958 as part of the boundary definition process under the terms agreed upon in the 2009 Exchange of Letters. The Orders in Council are also used by Brunei to define the boundaries of its territorial water in its preliminary submission to the Commission on the Limits of the Continental Shelf over its claims to the outer limits of its continental shelf.Online version available at the Commission's website.
The border can be divided into three sectors. From west to east, they are:
Western Sector Brunei's western border with Sarawak stretches seaward from the terminus of the land boundary at into sea following a set of five points to mark the "boundary in the neighbourhood of Tanjong Baram" defined by bearings and distances from a light-structure at .Sarawak (Definition of Boundaries) Order in Council 1958, Supplement IV online PDF.
Point Latitude (N) Longitude (E) Remarks Western Sector Border Boundary in the neighbourhood of Tanjong Baram as defined by the Sarawak (Definition of Boundaries) Order in Council 1958 0 4° 35' 45" 114° 4' 25" Defined as "the termination at the coast of the land boundary between the Colony of Sarawak and Brunei in approximate position bearing 090 degrees, distant 5.9 miles from the light-structure" 1 4° 39' 20" 114° 4' 18""A position bearing 058 ¼ degrees, distant 6.8 miles from the light-structure" 2 4° 39' 46" 114° 4' 22""A position bearing 055 ½ degrees, distant 7.1 miles from the light-structure" 3 4° 43' 38" 114° 3' 4""Thence along the arc of a circle, radius 4.6 miles, centred upon a point bearing 016 degrees, distant 4.8 miles from the light-structure, to a position bearing 030 degrees, distant 9.1 miles from the light-structure" 4End point at the 100-fathom depth contour, defined as "the intersection with the 100-fathom depth contour of a straight line drawn in a direction of 314 degrees from the position" defined in Point 3.
Western Brunei Bay Sector Brunei's border with Sarawak here consists of a boundary line in Brunei Bay between the mouth of the Pandaruan River in the east, and one of the mouths of the Brunei River in the west, and which encloses a stretch of Malaysian waters adjacent to the mouth of the Limbang River. The Sarawak (Definition of Boundaries) Order in Council 1958 sets ten points to enclose an area described as the "boundary in the approach to Batang Limbang" defined by bearings and distances from a beacon at .
Point Latitude (N) Longitude (E) Remarks Western Brunei Bay Sector Border Boundary in approach to Batang Limbang as defined by the Sarawak (Definition of Boundaries) Order in Council 1958 0 4° 50' 41" 115° 2' 42" Defined as "The termination of the land boundary between the Colony of Sarawak and Brunei at the northern extremity of the drying mud flat extending from Pulau Siarau in approximate position bearing 195 degrees, distant 0.75 miles from the beacon" 1 4° 51' 15" 115° 3' 13""A position bearing 114 degrees, distant 0.35 miles from the beacon" 2 4° 51' 22" 115° 3' 20""A position bearing 094 degrees, distant 0.44 miles from the beacon" 3 4° 51' 34" 115° 3' 36""A position bearing 077 degrees, distant 0.72 miles from the beacon" 4 4° 52' 15" 115° 4' 1""A position bearing 052 ½ degrees, distant 1.40 miles from the beacon" 5 4° 52' 23" 115° 3' 36""A position bearing 035 ½ degrees, distant 1.20 miles from the beacon" 6 4° 52' 28" 115° 3' 16""A position bearing 018 ½ degrees, distant 1.13 miles from the beacon" 7 4° 52' 36" 115° 2' 55""A position bearing 001 degrees, distant 1.20 miles from the beacon" 8 4° 52' 38" 115° 2' 45""A position bearing 353 degrees, distant 1.25 miles from the beacon" 9 4° 52' 50" 115° 2' 30""The termination of the land boundary between the Colony of Sarawak and Brunei in approximate position bearing 344 ½ degrees, distant 1.48 miles from the beacon"
Eastern Sector Brunei's eastern border with Sarawak stretches seaward from terminus of the eastern land border of the Sultanate's Temburong District at the mouth of the Bangau River with the Bay of Brunei, along straight lines joining a set of turning points until the Brunei-Sabah-Sarawak tripoint in the middle of the bay, as described in both the Sarawak (Definition of Boundaries) Order in Council 1958Section 2(1) of the Sarawak (Definition of Boundaries) Order in Council 1958 and North Borneo (Definition of Boundaries) Order in Council 1958Section 2(1) of the North Borneo (Definition of Boundaries) Order in Council 1958 as a "position bearing 050 degrees, distant 10.5 miles from Sapo Point light-structure".
The border, now with Sabah and based on the North Borneo (Definition of Boundaries) Order in Council 1958, then continues in straight lines joining a set of turning points to the mouth of Brunei Bay at a point defined as 310¾ degrees, distant 20.4 miles from Pelong Rocks light-structure which is sited at coordinates at . From this point, the border runs as a straight line drawn in a direction of 316 degrees from the said position until it intersects the 100 fathom isobath at a point with coordinates .
Point Latitude (N) Longitude (E) Remarks Eastern Sector Border Border with Sarawak as defined by the Sarawak (Definition of Boundaries) Order in Council 1958 0 4° 54' 50" 115° 9' 13" Defined as "The termination of the land boundary between the Colony of Sarawak and the State of Brunei in approximate position bearing 191 degrees, distant 4.05 miles from Sunda Spit beacon", which places it at the mouth of the Bangau River. 1 4° 55' 11" 115° 8' 49""A position bearing 198 degrees, distant 3.80 miles from Sunda Spit beacon" 2 4° 55' 36" 115° 8' 36""A position bearing 203 ½ degrees, distant 3.49 miles from Sunda Spit beacon" 3 4° 56' 2" 115° 7' 56""A position bearing 216 ½ degrees, distant 3.45 miles from Sunda Spit beacon" 4 4° 56' 14" 115° 7' 46""A position bearing 221 degrees, distant 3.40 miles from Sunda Spit beacon" 5 4° 56' 27" 115° 7' 45""A position bearing 223 ½ degrees, distant 3.25 miles from Sunda Spit beacon" 6 4° 57' 44" 115° 7' 56""A position bearing 242 ½ degrees, distant 2.32 miles from Sunda Spit beacon" 7 4° 59' 13" 115° 8' 41""A position bearing 287 ½ degrees, distant 1.37 miles from Sunda Spit beacon" 8 5° 0' 6" 115° 8' 57""A position bearing 321 degrees, distant 1.67 miles from Sunda Spit beacon" 9 5° 0' 49" 115° 9' 16""A position bearing 340 ¼ degrees, distant 2.15 miles from Sunda Spit beacon" 10 5° 1' 42" 115° 9' 51""A position bearing 357 degrees, distant 2.90 miles from Sunda Spit beacon" 11 5° 2' 13" 115° 10' 36""A position bearing 010 degrees, distant 3.47 miles from Sunda Spit beacon" 12 5° 4' 0" 115° 12' 31""A position bearing 025 ¾ degrees, distant 5.77 miles from Sunda Spit beacon" 13 5° 5' 57" 115° 14' 19""A position bearing 031 degrees, distant 8.35 miles from Sunda Spit beacon" Common point of the Brunei, Sabah and Sarawak border 14 5° 6' 30" 115° 15' 49""A position bearing 050 degrees, distant 10.5 miles from Sapo Point light-structure" Border with Sabah as defined by the Sabah (Definition of Boundaries) Order in Council 1958 15 5° 5' 48" 115° 13' 56""A position bearing 045 ½ degrees, distant 8.65 miles from Sapo Point light-structure" 16 5° 7' 2" 115° 6' 28""A position bearing 350 degrees, distant 7.40 miles from Sapo Point light-structure;" 17 5° 9' 20" 115° 03' 53""A position bearing 009 degrees, distant 4.65 miles from Pelong Rocks light-structure" 18 5° 9' 3" 114° 55' 44""A position bearing 300 ¼ degrees, distant 8.55 miles from Pelong Rocks light-structure" 19 5° 16' 9" 114° 49' 58""A position bearing 311 degrees, distant 17.4 miles from Pelong Rocks light-structure" 20 5° 18' 3" 114° 47' 39""A position bearing 310 ¾ degrees, distant 20.4 miles from Pelong Rocks light-structure" 21 5° 13' 52.2" 114° 55' 12"End point at the 100-fathom depth contour, defined as "the intersection with the 100-fathom depth contour of a straight line drawn in a direction of 316 degrees from the position" defined in Point 20.
The positions of the Sapo Point light structure, on Pulau Muara in Brunei, is given as , the Sunda Spit beacon, in Sarawak, is , and the Pelong Rocks light structure in Brunei is .
Continental shelf claim