Seoul Nowon United FC

In 2001, following the K League's decision to relocate the then-capital clubs to other cities, there was a desire to bring professional football back to the city of Seoul.

Following the 2002 Korea/Japan World Cup, Seoul's World Cup Stadium stood empty, except for the occasional international match. The Seoul Metropolitan government sought to offset not only the maintenance cost, but also the construction cost, by creating a new team in Seoul. Members of the online community, Seoul Citizens' Club Supporters' Group (서울시민구단 서포터 모임), along with the Red Devils Seoul Branch, had previously expressed the desire to bring football back to the capital, and saw this an opportunity. But the proposed cost of using Seoul's World Cup Stadium was set at 25 billion won, a price no company was willing to play to start a new club.

With no team or company interested, and the national stadium standing empty, the idea was proposed for two clubs to move to Seoul at a cost of 7.5 billion won each, with the Seoul Metropolitan Government contributing the remaining 10 billion won. Anyang's LG Cheetahs agreed to pay the combined 15 billion won and in 2004 became the new occupants of the World Cup Stadium, delivering a blow to the movement's plans to for a new team.

Despite the setback, the fan push continued, and the establishment of the K3 League in 2007 gave a realistic opportunity for involvement in the league set-up. Two amateur sides, Good Bu&Bu (Good Friend) and Youngseo FC (Jin Seoul), were merged to create the new club and the home venue of 69,950 capacity Seoul Olympic Stadium was chosen.

The club's first match was played on April 21, 2007, a 2–2 home draw with Changwon Dudae FC. Under the banner of “The True Seoul Citizen’s Club”, the team saw initial excitement and success, winning the inaugural K3 League title after a 3–0 aggregate victory over Hwaseong Shinwoo Electronics in the championship final.

In the years following their initial success, the team struggled with results and financial deficits. After leaving Seoul Olympic Stadium, they played at Hyochang Stadium before relocating to the 446 capacity Nowon Madeul Stadium in Nowon District, Northern Seoul. In 2019 the team's official name was changed to Seoul Nowon United FC to reflect their ties with Nowon District.

Since 2013, Seoul United have been involved in various youth projects in the Nowon District. Both male and female youth teams in various age categories were established and dissolved. In 2024 the U18 team was re-established.

In 2015 Seoul United formed a sister relationship with Japanese 3rd tier FC Ryukyu, with the intention to play each other once a year.

In 2021, the futsal team known as FS Seoul moved to Nowon and joined Seoul Nowon United. They are currently known as NowonHR FS and compete in the FK-League.

On 14 January 2025, two months before the start of the season, the club was handed a one-season suspension. The main reason was the failure of the club to reach an agreement with Nowon District regarding the use of Madeul Stadium, leaving them without a home ground. Following this suspension, the club announced that it would cease operations after 17 years in the league.

When the team disbanded, it was rumoured that they would restructure and revive the club, but these plans were not made public. Then, in May 2025, it was announced that the club had appointed Joo Seung-jin as its new manager. Joo was a long time coach and Assistant Manager at Suwon Samsung Bluewings FC, and manager of Hwaseong FC during their final year in the K3 League. The team would once again function as a private entity and renewed their agreement with Nowon District for the use of Madeul Stadium. It was further announced that they had already recruited players and would start playing practice matching in preparation for the 2026 K4 League season. However, a month later an article was published stating that Joo took a position as a coach at Daegu FC and Jeong Seong-hun, a former national team member, was to be the new manager.