Transjakarta (stylised in all-lowercase, often erroneously called Busway, sometimes shortened as TJ and branded as TiJe) or Jakarta BRT is a bus rapid transit (BRT) system in Jakarta, Indonesia. The first BRT system in Southeast Asia, it commenced operations on 15 January 2004 to provide a fast public transport system to help reduce rush hour traffic. The system is considered Jakarta's premier public transit offering. The buses run in dedicated lanes (busways), and ticket prices are subsidised by the regional government.

Transjakarta has the world's longest BRT system (251.2 km in length), which operates about 4,300 buses. Transjakarta aims to have 50 percent of its fleet be electric buses by 2027. By 2030, the aim is for the entire Transjakarta ecosystem to use electric buses. As of November 2023, it serves an average of 1.134 million passengers daily.

Transjakarta system is operated by municipally owned company PT Transportasi Jakarta. However, most of its fleet is operated by various companies aside of the company itself.

Transjakarta was conceived to provide a fast, comfortable, and affordable mass transportation system. The proposal for a BRT system in Jakarta was emerged in 2001. Governor of Jakarta at the time, Sutiyoso proposed four mass public transportation modes in Jakarta:

The MRT has larger passenger capacity and shorter travel time than the other proposals, but it required large foreign investments. At the time, Indonesia lost its investor confidence due to concerns over unstable domestic situations in the early 2000s as an aftermath of the fall of the New Order regime in 1998, so the MRT construction was unable to be realized yet. Among those four, the bus rapid transit was considered the most likely to be realized in a short time because it didn't require foreign investments.

The Institute for Transportation and Development Policy (ITDP) was an important party accompanying the BRT planning process. The initial concept was created by PT Pamintori Cipta, a transportation consultant who has frequently worked with the Jakarta Office of Transportation (Dinas Perhubungan Provinsi DKI Jakarta). Apart from the private sector, there were several other parties that also supporting this project, including the United States Agency for International Development (USAID) and University of Indonesia's Center for Transportation Studies (UI–CTS).

The buses were given lanes restricted to other traffic and separated by concrete blocks on the streets that became part of the busway routes. The first Transjakarta line opened to the public on 15 January 2004. It was free for the first two weeks, after which commercial operations started on 1 February 2004.

At present, Transjakarta has 14 primary routes and ten cross-corridor routes. In addition, there are about 200 "feeder" routes that serve beyond the exclusive busway corridors to serve satellite cities in Greater Jakarta under the 'Transjabodetabek' and 'Royaltrans' brands. The number of Transjakarta buses has also increased dramatically, from 605 buses in 2015 to 4,300 in 2020. The fare has remained Rp 3,500 (27 US cents) per passenger since operations began. The service set a record in 2018 when it carried 730,000 passengers per day, a significant jump from 331,000 per day in 2015. About 189.8 million passengers used Transjakarta in 2018 and targeted to serve one million passengers daily. In November 2020, Transjakarta won the 2021 Sustainable Transport Award.