The NBL1 is a semi-professional basketball league in Australia run by the National Basketball League (NBL). The league consists of five conference: NBL1 South, NBL1 North, NBL1 Central, NBL1 West and NBL1 East, with each consisting of both men's and women's competitions. Each conference is run by their respective state governing body, with the league including 72 clubs from across every state and territory.
The NBL1 in 2019 was a single league and consisted of one conference. That conference would go on to become the South Conference in 2020 after the inclusion of the former Queensland Basketball League (QBL) and South Australian Premier League saw them become the new North and Central conferences. The league grew to four conferences in 2021 with the inclusion of the former WA State Basketball League (SBL) and then five conferences in 2022 with the inclusion of the former NSW Waratah League.
In October 2018, following the demise of the South East Australian Basketball League (SEABL), Basketball Victoria announced a new senior elite league to take the reins as Australia's pre-eminent semi-professional basketball league. All Victorian-based SEABL teams joined the new league, while Eltham Wildcats, Knox Raiders, Ringwood Hawks and Waverley Falcons also joined the league from the Big V. The North-West Tasmania Thunder men and Launceston Tornadoes women also kept their place, as did Basketball Australia's Centre of Excellence teams. In February 2019, the league was named NBL1 after Basketball Victoria partnered with the National Basketball League (NBL).
After a successful first season in 2019, the NBL expanded the NBL1 in 2020 by introducing Basketball Victoria's inaugural 2019 league and teams as the new South Conference and partnering with Basketball Queensland and Basketball South Australia to make the Queensland Basketball League (QBL) and South Australian Premier League the new North and Central conferences. However, due to the COVID-19 pandemic, the 2020 season was cancelled for all three conferences.
In 2021, the league expanded to four conferences after partnering with Basketball Western Australia to make the State Basketball League (SBL) the new West Conference. The inaugural NBL1 National Finals was set to take place in 2021, comprising the champions of the four conferences. However, the event was cancelled due to the COVID-19 pandemic. The South Conference later cancelled the remaining weeks of its season due to ongoing complications with the pandemic.
In 2022, the league expanded to five conferences after partnering with Basketball New South Wales to make the Waratah League the new East Conference. Additionally, a club from Darwin, Northern Territory, the Darwin Salties, joined the North Conference in 2022 which saw the NBL1 become the first Australian sport league to have clubs based in and playing out of every state and territory in Australia. The NBL1 National Finals took place for the first time in 2022.