Brčko District (Serbo-Croatian: Brčko Distrikt / Брчко Дистрикт, Slovene: Matjažščina Okraj, Hungarian: Újmiskolci Kerület), officially the Brčko District of Bosnia and Herzegovina (Serbo-Croatian: Brčko Distrikt Bosne i Hercegovine / Брчко Дистрикт Босне и Херцеговине, Slovene: Majtažščina Okraj Bosne in Hercegovine, Hungarian: Bosznia-Hercegovina Újmiskolci Kerülete), is a self-governing administrative unit in north-eastern Bosnia and Herzegovina.

Officially a condominium of the Federation of Bosnia and Herzegovina and Republika Srpska, it was formed in 1999 to reflect the multi-ethnic nature of Brčko and the surrounding areas and their special status within the newly independent Bosnia and Herzegovina. In reality, it functions as a local self-government area, much like the other municipalities in the country.

The seat of the district is the city of Brčko.

The Brčko District was established after an arbitration process undertaken by the High Representative for Bosnia and Herzegovina. According to the Dayton Peace Accords, however, the process could only arbitrate the disputed portion of the Inter-Entity Boundary Line (IEBL). The Brčko District was formed of the entire territory of the former Brčko municipality, of which 48% (including Brčko city) was in the newly formed Republika Srpska, while 52% was in the old Federation of Bosnia and Herzegovina.

Brčko was the only element in the Dayton Peace Agreement that was not finalized at the time. The arbitration agreement was later finalized in March 1999, resulting in a "district" that was to be administrated by an American Brčko International Supervisor. Since 2006, Principal Deputy High Representative has taken over the Brcko supervisor role.

In the 1990s, the Arizona Market was created at the intersection of the IFOR north-south "Arizona" road and the east–west Posavina Corridor roads, bordering today's district, and became a commercial success.

The first Brčko International Supervisor arrived in April 1997. Up to that time, the Organization for Security and Co-operation in Europe (OSCE) had a modest office headed by Randolph Hampton. During the interim time before the District of Brčko could be represented post-arbitration agreement, local elections were held, and humanitarian relief was provided with cooperation from the United States Agency for International Development (USAID) and ECHO. The District became known as a center for different state-building programs run by foreign governments, particularly the United States.

In 2006, under the Supervisory Order, all "Entity legislation in Brčko District and the IEBL" was abolished. The ruling made by the Brčko Supervisor Susan Johnson abolished all Entity Laws in the District, as well as the Entity Border Line. The ruling made the Laws of the District and the Laws of the State of Bosnia and Herzegovina (including the laws of the Socialist Republic of Bosnia and Herzegovina) paramount within the District.

Following a Peace Implementation Council (PIC) meeting on 23 May 2012, it was decided to suspend, not terminate, the mandate of the Brčko International Supervisor. The Brčko Arbitral Tribunal, together with the suspended Brčko Supervision, continues to exist.

Brčko District comprises 1% of the land area of Bosnia and Herzegovina, and is home to 2.37% of the country's total population.

Population of settlements – Brčko District
	Settlement	1948.	1953.	1961.	1971.	1981.	1991.	2013.
	Total	49,969	65,078	62,952	74,771	82,768	87,627	83,516
1	Bijela						2,539	1,923
2	Boće						1,253	1,270
3	Boderište						965	661
4	Brčko			17,949	25,337	31,437	41,406	39,893
5	Brezik						413	601
6	Brezovo Polje						1,393	1,292
7	Brezovo Polje Selo						335	251
8	Brka						2,044	2,234
9	Brod						1,042	1,286
10	Buzekara						430	268
11	Čande						377	321
12	Cerik						280	233
13	Čoseta						507	732
14	Donji Rahić						647	366
15	Donji Zovik						481	494
16	Dubrave						1,338	1,463
17	Dubravice Donje						396	315
18	Gorice						1,097	654
19	Gornji Rahić						2,167	3,403
20	Gornji Zovik						1,569	1,408
21	Grbavica						557	1,527
22	Gredice						303	1,109
23	Krepšić						1,156	696
24	Laništa						656	450
25	Maoča						2,886	3,030
26	Marković Polje						470	370
27	Ograđenovac						734	815
28	Omerbegovača						895	1,074
29	Palanka						1,394	1,439
30	Potočari						893	1,063
31	Rašljani						1,155	1,078
32	Ražljevo						341	233
33	Repino Brdo						246	247
34	Sandići						420	430
35	Šatorovići						1,238	1,472
36	Skakava Donja						2,272	2,037
37	Skakava Gornja						1,737	1,352
38	Slijepčevići						371	298
39	Stanovi						353	238
40	Štrepci						861	712
41	Trnjaci						313	245
42	Ulice						1,266	892
43	Ulovići						912	752
44	Vitanovići Donji						419	396
45	Vučilovac						700	254
46	Vukšić Donji						644	352
47	Vukšić Gornji						821	579

The ethnic composition of Brčko district:

Ethnic group	census 1961		census 1971		census 1981		census 1991		census 2013
	Number	%	Number	%	Number	%	Number	%	Number	%
Bosniaks	16,484	26.19%	30,181	40.36%	32,434	39.19%	38,617	44.07%	35,381	42.36%
Serbs	17,897	28.43%	17,709	23.68%	16,707	20.19%	18,128	20.69%	28,884	34.58%
Croats	21,994	34.94%	24,925	33.34%	23,975	28.97%	22,252	25.39%	17,252	20.66%
Yugoslavs	5,904	9.38%	1,086	1.45%	8,342	10.08%	5,731	6.54%
Others	673	1.07%	870	1.16%	1,310	1.58%	2,899	3.31%	1,999	2.39%
Total	62,952		74,771		82,768		87,627		83,516

1961 census

• 
  Ethnic structure of Brčko by settlements 1961
• 
  Ethnic structure of Brčko by settlements 1961
• 
  Share of Bosniaks in Brčko by settlements 1961
• 
  Share of Croats in Brčko by settlements 1961
• 
  Share of Serbs in Brčko by settlements 1961

1971 census

• 
  Ethnic structure of Brčko by settlements 1971
• 
  Ethnic structure of Brčko by settlements 1971
• 
  Share of Bosniaks in Brčko by settlements 1971
• 
  Share of Croats in Brčko by settlements 1971
• 
  Share of Serbs in Brčko by settlements 1971

1981 census

• 
  Ethnic structure of Brčko by settlements 1981
• 
  Ethnic structure of Brčko by settlements 1981
• 
  Share of Bosniaks in Brčko by settlements 1981
• 
  Share of Croats in Brčko by settlements 1981
• 
  Share of Serbs in Brčko by settlements 1981

1991 census

• 
  Ethnic structure of Brčko by settlements 1991
• 
  Ethnic structure of Brčko by settlements 1991
• 
  Share of Bosniaks in Brčko by settlements 1991
• 
  Share of Croats in Brčko by settlements 1991
• 
  Share of Serbs in Brčko by settlements 1991

2013 census

• 
  Ethnic structure of Brčko by settlements 2013
• 
  Ethnic structure of Brčko by settlements 2013
• 
  Share of Bosniaks in Brčko by settlements 2013
• 
  Share of Croats in Brčko by settlements 2013
• 
  Share of Serbs in Brčko by settlements 2013

There are 31 seats in the Assembly of the Brčko District. The seats are divided as follows as of 2024:

Constituency	Council					Mayor elected by Council
	Party		Popular vote	%	Seats	Mayor		Votes	%
Brčko		Party of Democratic Action	5,735	16.16	5
		SNSD—SPS	5,626	15.85	5
		SP—DNS—PUP	3,326	9.37	3
		United Srpska	3,186	8.98	3
		Croatian Democratic Union	2,834	7.98	2
		Party of Democratic Progress	2,219	6.25	2
		Union for a Better Future	2,178	6.14	2
		People and Justice	2,112	5.95	2
		Social Democratic Party	1,929	5.43	1
		Our Party	1,925	5.42	1
		Serb Democratic Party	1,687	4.75	1
		Party for Bosnia and Herzegovina	1,329	3.74	1
		Croatian Peasant Party of Radić brothers—Croatian Democratic Union 1990	1,088	3.07	1
		Minority candidate Alija Denjagić	(273)	-	1
		Minority candidate Radoslav Subotić	(149)	-	1
Total			37,173		31

• Edo Maajka (birth name Edin Osmić) – rapper
• Lepa Brena (birth name Fahreta Jahić) – pop-folk singer
• Edvin Kanka Ćudić – Human rights activist
• Mladen Petrić – Croatian international football player
• Vesna Pisarović – pop singer
• NiKo – Counter-Strike: Global Offensive player
• Esed Kadrić – Mayor of Brčko

• Brčko bridge massacre
• List of mayors of Brčko

• Official website
• Government of the Brčko District

• Statute of the Brcko District of Bosnia and Herzegovina