Foundation The professional club was founded in 2011 by the
Sikkim Football Association (SFA), Baichung Bhutia, already competing in the
Sikkim Gold Cup and other all-India tournaments in the early years of their existence. The club revealed that they would compete in the
2011 I-League 2nd Division, in the quest for promotion to the I-League within the next three years.
2011–2012: 2nd Division seasons The club started their quest for the I-League on 27 February 2011. The club played their first match against
Langsning F.C. on 31 March 2012, in which they drew 2–2. United Sikkim won on 5 April 2011 against
North Imphal Sporting Association at the
Indira Gandhi Athletic Stadium in
Assam, by a score of 2–0. The club finished first in group A and qualified for the
2011 I-League 2nd Division final round, in which they only needed to finish in the top two for promotion. The club began final round with three consecutive draws against
Sporting Clube de Goa,
Royal Wahingdoh and
Shillong Lajong, before winning against
Mohammedan and
Southern Samity. Next, a draw to
Ar-Hima and a loss to
Vasco officially knocked United Sikkim out of contention for promotion and forced them to settle at fifth place for the season. The season including the
2012 I-League 2nd Division did not start well for United Sikkim. On 11 June 2011, it was announced that Johnny Menyongar would leave the club to join I-League team Shillong Lajong, as well as Indian internationals
Renedy Singh and
NS Manju few months later. However, after firing coach
Stanley Rozario, United Sikkim signed Belgian
Philippe De Ridder. The club re-signed
Nigerian players
Daniel Bedemi and
Quinton Jacobs. They began charge for the I-League for the second season in a row with a 3–2 victory over
Bhawanipore F.C. at the
Satindra Mohan Dev Stadium in
Assam on 2 February 2012. The club went on to win three more matches during the first round, against
Eagles,
Southern Samity and
Ar-Hima, in order to qualify for the final round. They won promotion on the last day of the season at home, in front of 30,000 fans, as United Sikkim drew
Mohammedan SC 1–1, with Daniel Bedemi scoring. On 13 November 2012, Bhutia was named the interim manager to replace Philippe De Ridder, after the club's heavy 1–10 defeat in an I-League match against
Prayag United at the
Salt Lake Stadium. In August 2012, United Sikkim took part in the Shillong Super Series Football Championship and faced teams like
A-League Wellington Phoenix and Shillong Lajong.
2012–2013: I-League It was reported that United Sikkim had started talks with Australian manager
Nathan Hall about a possible head coaching role. On 10 December 2012, it was confirmed that Hall had joined the club, replacing interim player-coach Bhaichung Bhutia. His first game came on 15 December against
Mumbai at the
Balewadi Sports Complex, in which United Sikkim lost 0–1. Hall managed to earn his first point in next match against
ONGC on 29 December in which his side drew 1–1 at the
Ambedkar Stadium, with
Nadong Bhutia scoring the first goal for United Sikkim under Hall. United Sikkim did not win a single game under Hall until 27 March 2013, when they managed a 5–0 victory over forced-relegated
Air India at Paljor Stadium. This would turn out to be United Sikkim's last win and points for the rest of the season, as the side lost its last four matches and was relegated to the I-League 2nd Division.
2013: Travel to Bhutan In March 2013, United Sikkim went to
Bhutan for training. In their first foreign tour, they played three friendly matches against local sides
Drukpol,
Yeedzin and
Zimdra at the
Changlimithang Stadium in
Thimphu. From July to August, they went to Bhutan again and participated in
2013 King's Cup, in which they moved to the knock-out stages. In the first semi-final, United Sikkim lost 2–4 to
Manang Marshyangdi of
Nepal.
2014: I-League 2nd Division They also participated in the
2014 I-League 2nd Division and moved to the
final round of
I-League Qualifiers, finishing on fourth position with seven points in eight matches.
2014–2018 On 18 December 2014, it was revealed by owner Bhaichung Bhutia that United Sikkim had decided to leave the competition as future of the I-League was dim due to the formation of ISL, and thus team would only participate in the local league. In 2016, they took part in
Bordoloi Trophy in
Assam. In the 2016 edition of Sikkim Governor's Gold Cup, the club reached quarter-finals. In February 2018, United Sikkim went to Nepal and participated in the 16th edition of
Aaha! Rara Gold Cup, in which they failed to reach the knock-out stages. It was the club's second campaign in Aaha! Rara Gold Cup, first being the 2017 edition, in which they tasted a 4–2 defeat in penalty shootout to Sahara Club of Pokhara.
2020–present The
All India Football Federation (AIFF) was all set to invite bids for vacant spot in the I-League and Gangtok-based United Sikkim Football Club were one of the front-runners to submit it for 2020–21 season. However, the bid was won by
Sudeva Moonlight (currently Sudeva Delhi) from
Delhi. In 2021, Bhaichung Bhutia, the owner of the club announced that it will revive its junior and senior teams while aiming to bring the Indian Super League (ISL) into the state, alongside focusing on its grassroots. They later took part in
Birat Gold Cup in
Nepal, in 2021. The club later featured in SFA Premier Division League. In October 2022, it was officially announced by the Centre for Bangladesh-India Friendship that United Sikkim is one of the three participating teams from India (others being United Kurseong and Jaigaon FC) for the inaugural edition of the
North Bengal International Gold Cup. == Club crest and kits ==